273    filD 


XPERIMENTAL 
CHEMISTRY 


BY  WALTER  MONROE 


J&N     61906 


LIBRARY 

OF   THE 

UNIVERSITY  OF  CALIFORNIA. 

GIFT  OF" 

^  0  ^  r 

/^Vw^.. HA  ,...iL, 

C/^S5 


EXPERIMENTAL  CHEMISTRY 

FOR 

HIGH  SCHOOL  STUDENTS 


BY 


WALTER  MONROE, 

Instructor  in  Chemistry  in  the  Monrovia  High  School 


MONROVIA,    CALIFORNIA, 

1899 


COPYRIGHTED    1899 

BY 

WALTER    MONROE 


Commercial  Printing  House 
Los  Angeles 


PREFACE. 

(HIS  course  of  experiments  has  been  arranged  for 
students  in  high  schools,  and  is  intended  to  lead 
directly  to  the  courses  in  the  State  University. 
Since  many  of  the  principles  of  chemistry  are  founded 
upon  quantitative  relations,  a  number  of  such  experiments 
has  been  introduced;  but  no  exercise  has  been  incorpor- 
ated into  the  course  that  has  not  been  successfully  per- 
formed. Special  care  has  been  taken  in  clearly  describing 
the  experiments,  so  that  pupils  may  not  fail  to  obtain 
good  results.  Considerable  attention  has  also  been  given 
by  questions  and  suggestions  to  cause  the  student  to  think 
carefully  over  observed  phenomena. 

The  use  of  symbols  has  been  avoided  in  the  earlier 
stages  of  the  work,  and  qualitative  analysis  has  been 
entirely  omitted.  Very  little  of  real  value  can  be 
accomplished  in  the  way  of  qualitative  analysis  in  so 
short  a  time. 

A  number  of  the  most  important  elements  and  their 
compounds  has  been  considered,  and  the  experiments  out- 
lined are  only  those  which  may  be  performed  by  the 
student  during  the  year.  The  course  may  be  modified, 
whenever  desirable,  by  supplementary  directions  prepared 
by  the  instructor.  The  writer  is  of  the  opinion  that 
a  few  elements  and  their  most  important  compounds 
studied  carefully,  are  of  much  more  value  than  a  great 
many  studied  hurriedly. 

The  exercises  are  intended  to  develop  in  the  pupil  a 

140475 


4  PREFACE 

*  'scientific  habit  of  thought' '  and  lead  him  to  discover  for 
himself  by  a  purely  inductive  method  many  of  the  funda- 
mental principles  of  the  science. 

A  course   of  recitations,    and   an   occasional    lecture 
illustrated  by  experiments  should  accompany  the  labora 
tory  work.     The  note-book  should  be  used  in  the  labora- 
tory only,  so  that  it  may  always  represent  the  pupil's  own 
thoughts. 

Large  "folders"  with  perforated  paper  that  may  be 
removed  make  the  best  laboratory  note-books.  The 
written  sheets  may  be  passed  in  for  examination  by  the 
instructor,  and  afterwards  fastened  in  the  folders  and  kept 
for  future  reference. 

Very  few  directions  have  been  given  to  pupils,  for 
these  are  best  left  to  the  discretion  of  the  teacher. 

The  writer  is  indebted  to  Prof.  Rising  of  the  State 
University  for  many  valuable  suggestions.  It  is  likewise 
a  pleasure  to  acknowledge  the  assistance  received  from 
Mr.  Sharwood,  formerly  of  the  University,  who  has  so 
kindly  aided  in  the  presentation  of  the  book.  Much  of 
the  material  has  been  adapted  from  his  course  on  the 
"General  Laws  of  Chemical  Action." 

It  was  not  the  intention  to  have  this  course  put  into 
print  until  next  year;  but  the  demand  for  the  work  by  a 
number  of  instructors  has  induced  the  author  to  have  a 
limited  number  printed  for  use  this  year.  Next  year  the 
book  will  appear  in  better  form,  and  with  it  a  text  book 
which  is  now  in  preparation  and  especially  adapted  to  the 
course.  Further  suggestions  from  the  instructors  in 
chemistry  at  the  University,  and  from  teachers  who  may 
use  the  book  the  coming  year  will  be  thankfully  received. 

WALTER  MONROE. 
Monrovia,   Cal.y  June  75, 


CONTENTS. 
PART   I. 

THE    NON-METALS    AND    THEIR    COMPOUNDS. 


EXP.    NO. 


1  Physical  and  Chemical  Changes. 

2  Mechanical  Mixture  and  Chemical  Compound. 
3-5  Oxygen,  Preparation  and  Properties. 

6-9  Hydrogen,  Preparation  and  Properties. 

10-13  Water. 

14  Estimation  of  Water  in  Copper  Sulphate. 
(  Volumetric  Measurement  of  Gases. 
{  Equivalent  Weight  of  Zinc  and  Magnesium. 

1 6  Nitrogen,  Preparation  and  Properties. 

17  Composition  of  the  Atmosphere. 

1 8  Ammonia,  Preparation  and  Properties. 

19  Nitrous  Oxide,      " 
2  .  Nitric  Oxide, 

21  Nitric  Acid, 

22  Hydrochloric  Acid,   Preparation  and  Properties. 

23  Chlorine, 
24-25  Carbon, 

26  Carbon  Dioxide, 

27  Carbon  Monoxide,  "  "  " 

28  Flame,   Combustion,   Heat,  Light,  etc. 

29  Sulphur  and  Its  Properties. 

30  Sulphur  Dioxide,   Preparation  and  Properties. 

31  Hydrogen  Sulphide,          "  "  " 

32  Sulphuric  Acid,  "  "  " 

33  Acids,   Bases,  Salts,  etc. 

34  Neutralization. 


CONTENTS. 

PART  II. 

THK    METALS    AND    THEIR     COMPOUNDS. 


EXP.   NO. 


35  Potassium. 

36  Potassium  Compounds. 

37  Sodium. 

38  Sodium  Compounds. 

39  Ammonium  Compounds. 

40  Calcium  Compounds. 

41  Zinc. 

42  Zinc  Compounds. 

43-44  Oxidation  and  Reduction. 

45  Iron. 

46  Iron  Compounds. 

47  Copper. 

48  Equivalent  Weight  of  Copper. 

49  Lead  and  Its  Compounds. 
50—51  Silver  and  Its  Compounds. 

52  Mercury  and  Its  Compounds. 

53  Action  of  Acids  on  the  Metals. 

54  Chlorides. 

55  Oxides. 

56  Hydroxides. 

57  Sulphides. 

58  Nitrates. 

59  Sulphates. 

60  Carbonates. 

6 1  Crystallization. 

62  Determination  of  Atomic  Weights. 


CONTENTS 


APPENDIX. 

Table    of    Principal    Elements,    Atomic     Weights    and 

Symbols. 
Complete  List   of   Chemicals   and    Apparatus    Required 

for  the  Course. 
Individual  Apparatus. 
Preparation  of  Solutions. 
Addresses  of  Supply  Houses. 


GENERAL  DIRECTIONS. 

Students  should  provide  themselves  with  a  towel, 
some  pieces  of  cloths,  and  an  apron — one  with  sleeves  is 
the  best  protection. 

Keep  your  desk  in  as  good  order  as  possible;  and 
before  leaving  the  laboratory,  see  that  your  apparatus  is 
clean  and  the  table  dry.  Never  use  dirty  apparatus. 
Glass  vessels  should  be  cleaned  as  soon  after  use  as  possi- 
ble, rinsed  and  left  to  drain  and  dry  —  not  wiped  unless 
required  for  immediate  use.  No  one  can  do  good  work 
in  chemistry  who  neglects  these  essential  points. 

Do  not  put  down  the  stopper  when  using  a  re-agent 
bottle,  but  hold  it  between  the  fingers.  Any  excess  of  a 
re-agent  must  not  be  poured  back  into  the  re-agent  bottle. 
Always  see  that  your  flasks  and  tubes  are  dry  on  the  out- 
side before  heating,  and  apply  the  heat  gently  at  first. 

Use  great  care  in  handling  the  strong  acids  and  alka- 
lies. Forceps  should  be  used  in  handling  phosphorus, 
potassium,  and  sodium.  Do  not  perform  experiments 
outside  of  the  regular  work  without  permission  as  serious 
accidents  sometimes  occur 

Before  commencing  an  experiment,  read  the  directions 
carefully,  and  ascertain  the  object  of  it.  Always  ask  for 
information  when  you  are  in  doubt.  The  quality  of  the 
work  done  by  each  student  and  his  ability  to  draw  cor- 
rect conclusions  from  observed  facts,  is  of  far  more  value 
than  the  bare  number  of  experiments  performed. 

Watch  carefully  for  changes  that  may  take  place,  and 
write  in  your  note-book  in  the  laboratory  an  account  of 
the  experiment  as  you  have  performed  it,  (a  sketch  of  the 


10  GENERAL  DIRECTIONS 

apparatus  will  quite  often  save  time  in  description)  and 
state  any  conclusions  you  have  been  able  to  draw.  Be 
careful  to  note  everything  the  experiment  shows,  and 
answer  all  questions  fully. 

Write  the  description  neatly,  accurately,  and  in  good 
English.  Do  not  use  abbreviations  for  chemicals,  but 
write  the  name  in  full.  When  your  instructor  performs 
an  experiment,  write  an  account  of  it  just  as  if  you  had 
performed  it  yourself. 


PRELIMINARY   WORK. 


Make  yourself  thoroughly  familiar  with  the  practical 
use  of  the  metrical  standards,  and  learn  to  estimate  vol- 
umes in  cubic  centimeters. 

Graduate  a  test  tube  to  measure  5  and  10CC  by  pour- 
ing water  from  a  graduate  into  the  test  tube.  Mark  the 
level  of  the  water  by  a  small  file  scratch.  For  most 
experiments,  not  quantitative,  the  amounts  to  be  taken 
are  merely  approximate  and  may  be  weighed  on  paper  on 
a  rough  balance.  Volumes  of  liquids  can  be  measured 
in  graduated  vessels. 

Under  the  direction  of  your  teacher,  learn  to  do  the 
following  well: — Bend  glass  tubing  and  round  the  ends, 
draw  out  tubing,  close  the  ends  of  a  glass  tube,  make 
bulbs,  bore  corks  and  fit  tubes  in  them.  Always  have 
your  apparatus  neatly  arranged.  Ask  your  teacher  to 
assist  you  in  fitting  up  apparatus  until  you  become 
familiar  with  the  work. 


PART    I. 

EXPERIMENTS. 

THE   NON-METALS   AND   THEIR  COMPOUNDS. 

PHYSICAL    CHANGE    AND    CHEMICAL    CHANGE. 

1.  Changes  which  do  not  alter  the  nature  or  compo- 
sition of  substances  are  known  as  physical  changes.  Ice 
may  change  to  water  and  water  to  steam,  but  the  compo- 
sition of  the  substance  is  unchanged  and  the  changes 
are  physical. 

Changes  in  the  nature  and  composition  of  substances 
as  well  as  a  change  in  properties  are  chemical  changes. 
The  burning  of  wood  and  the  rusting  of  iron  are  exam- 
ples of  chemical  change. 

(a)  Dissolve  2  grams  of  sugar  in  about  5CC  of  water. 
Taste  the    solution.       What    change   has   taken    place? 
Always  give  reasons  for  your  answers.       Add  slowly  5CC 
of   concentrated   sulphuric   acid.     Note   any   change   of 
color,  or  temperature  of  the  tube.       Is   there  any  sugar 
left?     What  kind  of  a  change  has  taken  place? 

(b)  Dissolve  a  gram  of  salt  in  10CC  of  water  in   an 
evaporating  dish.     Evaporate  todryness  and  examine  the 
residue.     What  is  its  color  and  taste?     Name  the  change 
that  took  place. 

(c)  Hold  a  piece  of  platinum  wire  in  the  flame  of 
your   lamp,    remove  and  allow  to  cool.     Repeat  with  a 
piece  of  magnesium  ribbon;  hold  the  magnesium  with  a 
pair   of  pincers.        What    change    takes  place  in    each 
case?     Give  reasons.       Mention  other  changes  similar  to 
these  with  which  you  are  familiar. 


12  EXPERIMENTAL  CHEMISTRY 

MECHANICAL    MIXTURE    AND    CHEMICAL    COMPOUND. 

2.  (a)  Mix  intimately  about  one  gram  of  flowers  of 
sulphur  with  an  equal  weight  of  fine  iron  filings.  Exam- 
ine the  mixture.  Can  you  distinguish  the  particles  of 
iron  and  those  of  sulphur?  Examine  again  with  a  lens. 

(b)  Spread  some  of  the  mixture  on  a  piece  of  paper, 
and  pass  a  magnet  over  it.    What  is  the  effect?   The  oper- 
ation may  be  repeated  a  number  of  times  if  necessary. 

(c)  Put  a  small  quantity  of  the  mixture  in  a  test 
tube   and  cover  well  with  carbon  disulphide.      (Carbon 
disulphide  is  a  very  volatile  liquid  and   should  never  be 
heated.)      Shake   vigorously   several   times,    and  notice 
whether  any  change  takes  place.       Filter  the  substance 
(ask  for    directions);    catch   the   filtrate  upon   a   watch 
glass,  and  allow  it  to  evaporate.     What  is  left  on  the  filter 
paper?       Allow  it  to  become  dry  and  test  with  a  magnet. 
What  is  the  color  of  the  substance  on  the  watch  glass? 
What  is  it?      Has  the  separation  of  the  iron  and  sulphur 
been  accomplished  by  physical  or  chemical  processes? 

(d)  Take  all  but  a  small  quantity  of  the   mixture 
and  place  it  in  a  small  ignition  tube.       Heat  strongly  for 
some   time   and   observe   closely   the  changes  that  take 
place.       After  the  action  is  over  and  the  tube  is  cooled, 
break   it   and   catch   the   contents  on  a  piece   of  paper. 
Compare     the    substance     with    the    original    mixture. 
Examine  it  with  the  lens,  magnet,  and  carbon  disulphide. 
What  kind  of  a  change  has  taken  place? 


EXPERIMENTAL  CHEMISTRY  13 

• 

OXYGEN. 

3.  (a)  Mix  intimately,  without  pulverizing,  25 
grams  of  coarsely  powdered  potassium  chlorate  with  an 
equal  weight  of  pure  coarsely  powdered  manganese  diox- 
ide. Explosions  sometimes  occur  by  using  impure  man- 
ganese dioxide.  Test  the  mixture  by  heating  a  little  in 
a  test  tube.  If  no  violent  action  takes  place,  put  the 
mixture  in  a  retort  (copper,  if  obtainable),  or  a  flask,  and 
insert  a  delivery  tube.  Heat  the  retort  and  fill  several 
receivers  (cylinders  or  wide-mouthed  bottles)  with  the 
gas  by  the  displacement  of  water. 

(b)  Put   a    lighted  splinter    into  a   small  receiver; 
remove  it  and  put  it  in  again  while  glowing.     Does  oxy- 
gen support   combustion?     Inhale    a   little   of  the   gas. 
What  can  you  say  of  its  odor,  taste  and  appearance? 

(c)  Put  some  sulphur  into  a  deflagrating-spoon   (a 
piece  of  crayon  hollowed  out  and  attached  to  a  copper 
wire  will  answer )   and  hold  it  in  one   of  the  receivers. 
Into  another  receiver  introduce  a  piece  of  charcoal;  and 
into   a  third,    a  small  piece  of  phosphorus.       L,et  them 
stand  a  few  minutes,   and  note  any  changes  that   take 
place. 

(d)  Repeat  with  the  same  elements,  but  ignite  them 
before  introducing  into  the  receivers.     How  does  oxygen 
act  upon  substances  at  ordinary  temperatures  and  at  high 
temperatures? 

(e)  Fill  three  test  tubes  with  oxygen  and  put  a  piece 
of  dry  phosphorus  into  one,  a  piece  of  roll  sulphur  into 
another,  and  a  piece  of  charcoal  into  the  third.      Cork 
the    tubes   loosely,  and   place  them  in  a  beaker   of  cold 
water.       Heat  the  water  slowly,  or  pour  boiling   water 
slowly  into  the  cold.      Observe   the  changes  that   take 


14  EXPERIMENTAL  CHEMISTRY 

place.       Which  element  has  the  lowest  kindling  tempera- 
ture,  and  which  the  highest? 

4.  It  has  been  found  by  numerous  experiments  that 
whether  a  substance  burns  in  pure  oxygen  or  in  the  air, 
the  result  is  generally  the  same 

(a)  Ask  for  directions  for  using  the  delicate  balance, 
and  weigh  accurately  a  porcelain  crucible  which  has  been 
previously  heated  and  allowed  to  cool,  or  which  has  been 
left  in  a  desiccator  for  some  time.     Why?     Ask  if  you  do 
not  know. 

(b)  Take   about  one-half  gram  of  magnesium  rib- 
bon, weigh  accurately  and  place  it  in  the  crucible.    Place 
the  crucible  on  a  triangle  over  a  flame  and  heat  it  until 
the  magnesium  is  converted  into  a  powder,  and  then  place 
it  in  a  desiccator  and  allow ,it  to  cool. 

(c)  Weigh   the    crucible    and   contents    accurately. 
How  has  the  magnesium  changed  in  weight?      Note  any 
change  in  appearance,  conduct,  etc.,  of  the  magnesium, 

1  and  state  what  the  experiment  shows. 

Lead  may  be  used  in  this  experiment  instead  of  mag- 
nesium. Use  about  a  gram;  but  before  weighing,  it 
should  be  brightened  with  sandpaper,  or  have  the  dark 
part  cut  off  with  a  sharp  knife.  After  the  lead  is  melted, 
it  should  be  stirred  continually  with  a  stout  iron  wire 
until  it  ceases  to  be  in  a  liquid  form. 

5.  (a)    Put  about  one  gram  of  mercuric  oxide  in  a  hard 
glass  tube,  and  insert  a  delivery  tube.      Heat  the  tube  to 
redness  if  necessary  and  collect  the  gas  in  a  test  tube  or 
a   wide-mouthed   bottle   over   water.     Test  the  gas  col- 
lected.    How  do  you  know  what  it  is?     Note  any  change 
that  has  taken  place  in  the  mercuric  oxide. 

(b)  Repeat  (a)  using  about  four  grams  of  manganese 
dioxide  instead  of  the  mercuric  oxide. 


EXPERIMENTAL  CHEMISTRY  15 

HYDROGEN. 

6.  (a)     Place  15  to  20  grams  of  granulated  zinc  in 
a  flask  or  Wolff's  bottle;  attach  a  delivery   tube,    and 
through  a  second  opening  insert  a  thistle  or  funnel  tube. 
Add  about  100CC  of  dilute  hydrochloric  acid  or  sulphuric 
acid.       What  is  the  effect?      Allow  time  for  the  air  to  be 
expelled  from  the  generator  and  tube,  and  then  fill  several 
cylinders  or  bottles  with  gas  by  the  displacement  of  water. 
Fill  a  test  tube  with  the  gas,  invert  it  and  bring  a  lighted 
match  to  its  mouth.    What  happens?      I/ight  a  candle  or 
splinter  and  introduce  it  into  one  of  the  vessels  of  gas, 
having    the  mouth    of  the  receiver   downward.       Does 
hydrogen  behave  like  oxygen? 

(b)  Take  two  vessels  containing  the  gas;  place  one ' 
with  its  mouth  upward,  the  other  with  its  mouth  down- 
ward.      Uncover  both  vessels  and  after  a  few  moments 
introduce  a  lighted  taper  into  each.      Bxplain  the  differ- 
ence. 

(c)  Take  a  cylinder  or  bottle  containing  air  and  pour 
the  gas  from  one  of  the  receivers  into  it.     How  must  the 
vessels  be  held?     How  can  you  tell  that  the  gas  has  been 
poured   from  one  vessel  to  the  other?       What  does  the 
experiment  show? 

(d)  Collect  some  of  the  gas  from  the  generator  after 
passing  it  through  a  bottle  containing  a  solution  of  potas- 
aium  permanganate.     Has  hydrogen  any  odor,    taste  or 
color?      What  is  the  use  of  the  potassium  permanganate? 

7.  (a)     Arrange   an   apparatus   as   in    the  previous 
experiment,  but  instead  of  the  delivery  tube,  attach  a  U- 
shaped  tube  filled  with  calcium  chloride.    Roll  up  a  piece 
of  platinum  foil  so  as  to  make  a  small  tube  and  seal  it  to 
one  end  of  a  glass  tube  about  15cm  long.      Connect  the 


16  EXPERIMENTAL  CHEMISTRY 

other  end  of  the  glass  tube  to  the  calcium  chloride  tube 
so  that  the  platinum  point  will  be  almost  in  a  vertical 
position. 

(b)  Add  dilute  hydrochloric  acid  and  after  action 
has  been  going  on  long  enough  to  expel  all  air,  light  the 
hydrogen  escaping  from  the  jet.  (It  is  well  to  test  the 
gas  before  lighting.  How?  Ask  if  you  do  not  know. 
Wrap  a  towel  around  the  flask  to  prevent  any  serious 
accident  in  case  of  an  explosion.)  Place  a  bell-jar  or 
other  wide-mouthed  vessel  over  the  flame  at  an  angle,  and 
examine  after  a  few  minutes.  Explain  the  chemical 
change  that  takes  place  when  hydrogen  burns  in  air. 
What  is  the  use  of  the  calcium  chloride  tube?  Why  is 
the  platinum  tube  used  in  the  end  of  the  glass  tube? 
What  is  the  appearance  of  the  hydrogen  flame? 

8.  (a)     Take  an  iron  gas  or  water  pipe  about  50cm 
long  and  20mm  internal  diameter,  and  fill  the  middle  por- 
tion with  iron  turnings.       Fasten  the  pipe  in  a  horizontal 
position  by  means  of  a  clamp   attached  near  one   end. 
Partly  fill  a  flask  with  water,   place  it  on  a  ring  stand, 
and   connect  with  one  end  of  the   iron   pipe.     Insert  a 
delivery  tube  in  the  other  end  of  the  pipe  and  arrange  to 
collect  gas  over  water.      Heat  the  iron  pipe  to  redness  in 
the  center,  and  boil  the  water  in  the  flask. 

(b)  Collect  several  samples  of  the  gas  and  test  them. 
What  is  the  gas?  Give  reasons.  After  the  tube  has 
cooled,  examine  the  iron  turnings.  Explain  the  changes 
that  have  taken  place  during  the  experiment. 

9.  (a)     Fit  a  porous  earthen  cup  to  a  glass  tube  about 
25  or  30cm  long,   having  a  small  internal  diameter.     (In- 
stead of  the  porous  cup,  a  plaster  of  Paris  plug  may  be 
inserted  in  the  end  of  the  glass  tube  which  may,   in  this 
case,    be   shorter  and   about  2cm   in    internal  diameter.) 


EXPERIMENTAL  CHEMISTRY  17 

Put  the  other  end  of  the  tube  through  a  cork  in  one  neck 
of  a  Wolff's  bottle  containing  some  water  colored  with 
litmus,  or  any  other  coloring  matter.  Do  not  pass  the 
tube  below  the  surface  of  the  water.  Through  the  other 
neck  of  the  bottle  pass  a  small  glass  tube  below  the  sur- 
face of  the  water.  The  upper  end  of  this  tube  should 
extend  above  the  bottle  about  10cm,  be  bent  outward 
slightly,  and  drawn  out  at  the  end  to  a  small  opening. 

(b)  Fill  a  bell-jar  with  dry  hydrogen  by  the  dis- 
placement of  air,  and  bring  it  over  the  porous  cup.  Note 
what  happens  and  explain  all  that  you  have  seen.  Does 
the  bell-jar  filled  with  air  produce  the  same  effect? 

WATER. 

10.  Procure  the   apparatus   for   the    electrolysis   of 
water,  and  pour  water  into  the  glass  vessel  until  the  plat- 
inum electrodes  are  below  the  surface.       Take   two  large 
test  tubes  of  the  same  size,  and  fill  them  with  water  con- 
taining a  small  amount  of  sulphuric  acid.  "     Invert  the 
test  tubes  and  place  them  over  the  platinum  electrodes; 
then  pour  into  the  glass  vessel  about  one-twelfth  as  much 
strong  sulphuric  acid  as  it  contains  water.      Water  alone 
will  not  conduct  a  current,  but  when  sulphuric  acid  is 
added  it  acquires  the  power  to  convey  the  current.     Con- 
nect a  battery  of  two  or  three  cells  in  series  to  the  copper 
wires  in  connection  with  the  platinum  electrodes.     Notice 
the  electrodes.     When   the   water   has   been   completely 
forced  out  of  one  tube,  how  full  is  the  other?       Test  the 
gas  thus  collected.     How  do  you  know  what  the  gasses 
are?     Which  gas  collects  the  faster?     In  what  proportion 
do  the  two  gasses  unite  to  form  water? 

11.  From  the  knowledge  you   already  have   of  the 
behavior  of  water,  state  its  boiling  and  freezing  points. 
At  what  temperature  does  it  weigh  most?       What  is  the 


18  EXPERIMENTAL  CHEMISTRY 

weight  of  one  cubic  centimeter  at  that  temperature? 
Is  the  temperature  at  which  water  boils  affected  by  the 
pressure  under  which  it  boils? 

(a)  Fill  a  flask  of  about  one  liter  capacity  one-third 
full  of  water  from  the  hydrant  and  connect  it  with  a  con- 
denser.      Distil  about  50  to  100CC  of  the  water  and  com- 
pare it  with  the  hydrant  water  as  to  taste,  odor  and  color. 

(b)  Evaporate  to  dry  ness — in  a  watch  glass  set  over 
a  beaker  of  water,  or  in  an  evaporating  dish — about  5CC  of 
the  distilled  water. 

(c)  Treat  in  a  similar  manner  an  equal  amount  of 
water  from  the  hydrant.     Compare  results.       Could  sea 
water  be  made  fit  to  drink  by  distillation? 

12.  (a)     Heat  about   one   gram  of  copper  sulphate 
crystals  in  a  small  test  tube.       Observe  what  takes  place. 

(b)  Repeat  (a)  using  one  gram  of  alum. 

(c)  Treat  in  a  similar  manner  potassium  bichromate 
crystals  and  compare  with  (a)  and  (b). 

(d)  Place   a  few  crystals   of  clear  sodium   sulphate 
(Glauber's  salt)  on  a  watch  glass  and  leave  exposed  to  the 
air  until  the  next  day. 

(e)  Treat  similarly  a  few  pieces  of  calcium  chloride. 
Compare  with  (d). 

13.  Nearly   all   substances  dissolve  more  or  less  in 
water.      Platinum,  however,  is  insoluble.      Some  liquids 
are  soluble  in  water  in  all  proportions,  some  are  only  par- 
tially soluble,  while  liquids  like  oils  are  very  slightly  sol- 
uble.    The  solubility   of  a  substance  depends  upon  the 
temperature,  but  it  is  always  definite  for  a  given  tempera- 
ture.      The  solubility  of  solids  generally  increases  with 
the   temperature;  but  the   solubility   of  gases   decreases 
with  an  increase  of  temperature. 

(a)     Put  one  gram  of  powdered  potassium  chlorate 


EXPERIMENTAL  CHEMISTRY  19 

(weighed  on  a  balance)  in  a  test  tube,  add  three  or  four 
cubic  centimeters  of  water  and  heat  to  boiling.  Exam- 
ine the  solution;  allow  it  to  cool  and  examine  again. 

(b)  Add  about  15CC  of  water  and  heat  till  completely 
clear;  cool  and  compare  with  (a). 

(c)  Put  5CC  of  cold  water  in  a  test  tube  and  add  a 
few  drops  of  carbon  bisulphide.       Shake  well  and  let  it 
stand  a  few  minutes.     Examine. 

(d)  Pour  5CC  of  water  in  a  test  tube  and  add  a  few 
drops  of  ether.       Shake,  let  stand  and  examine;    add  a 
little  more  ether,  and  again  examine;  finally  add  4  or  5CC 
more  and  examine  again. 

(e)  Repeat  (d)  using  alcohol  instead  of  ether. 

ESTIMATION    OF    WATER    IN    COPPER    SULPHATE. 

14.  Dry  and  weigh  a  small  porcelain  crucible.  (See 
directions,  Exp.  4.)  Introduce  into  it  about  a  gram  of 
bright  crystals  of  pure  copper  sulphate,  slightly  powdered 
and  accurately  weighed.  Heat  in  an  oven  (or  on  asbestos 
cloth)  for  at  least  an  hour  at  a  temperature  between  100° 
and  110°  C.  Cool  in  a  desiccator  and  weigh.  Heat  the 
crucible  and  contents  again  under  similar  conditions  for 
about  half  an  hour,  cool  and  weigh  as  before.  Continue 
the  heating  until  you  find  the  weight  constant.  Now  heat 
over  a  flame  almost  to  a  low  red  heat  for  about  fifteen 
minutes;  cool  in  a  desiccator  and  weigh.  Calculate  the 
amount  of  water  expelled  below  110°  C.;  also  the  amount 
expelled  between  110°  and  low  red  heat.  What  fraction  is 
this  last  quantity  of  the  whole  amount  of  water  expelled? 
Calculate  the  percentage  of  water  in  the  blue  crystals 
taken. 

(b)  Put  the  dry  copper  sulphate  in  a  test  tube  and 
add  a  few  drops  of  water.  Note  any  change  in  appear- 
ance and  temperature. 


20  EXPERIMENTAL  CHEMISTRY 

VOLUMETRIC   MEASUREMENT    OF   GASES. 

If  has  been  found  by  experiment  that  the  volume  of  a 
gas  varies  with  the  temperature  and  pressure  as  follows: 

(a)  The   volume   of  a   given   quantity    of   dry   gas 
increases  ^   part  of  its  volume  at  zero  Centigrade  for 
each  rise  in  temperature  of  one  degree  Centigrade.     (Law 
of  Charles,   also  law  of  Gay-Lussac.)     Taking  — 273  as 
absolute  zero  and  273  plus  the  temperature  Centigrade 
the  absolute  temperature,  the  volume  varies  as  the  abso- 
lute temperature  divided  by  the  pressure. 

(b)  The  volume  of  a  confined  mass  of  gas  is  inversely 
proportional  to  the  pressure  to  which  it  is  exposed.     The 
volume  times  the  pressure  is  equal  to  a  constant  (Law  of 
Boyle,  also  Marriotte's  Law).     The  atmospheric  pressure 
varies  with  the  height  above  sea-level,  but  it    approxi- 
mates to  that  of  a  column  of  mercury  760mm  high  which 
is  taken  as  the  standard. 

From  the  above  laws  we  get  the  following  formula 
which  may  be  used  to  determine  \vhat  volume  a  gas, 
measured  at  one  temperature  and  pressure,  would  occupy 
at  another: 

Let  V  represent  the  volume  of  a  given  mass  of  gas  at 
0°  C.  and  760mm  pressure. 

Its  volume  at  1°  C.  and  760mm  press ure=V-f^-3V. 

Its  volume  at  2°  C.  and760mm  pressure=V-j-~V. 

Its  volume  at  t°  C.  and  760mm  pressure=V+ ~  V.  =: 

273+tx 
Vl    273    )' 

Its  volume  at  t°  C.  andpmmpressure=V(^)-^. 

The  volume  of  a  gas  in  contact  with  water  is  increased 
owing  to  pressure  of  water  vapor.  Correction  may  be 
made  by  subtracting  from  the  given  barometric  pressure 
the  tension  of  aqueous  vapor  at  the  given  temperature; 


EXPERIMENTAL  CHEMISTRY  21 

that  is,  substitute  for  p.  in  the  formula  the  observed 
barometric  reading  ^ninus  the  tension  of  water  vapor  at 
the  temperature  /  centigrade. 

TENSION    OF    WATER    VAPOR    FOR    DIFFERENT   TEMPER- 
ATURES. 
Temp.  C.  Tension  of  vapor        Temp.  C.  Tension  of  vapor 

0° 4.6mm  21° t, 18.49mm 

4° r.... 6.0  "  22° ....19.69" 

8° 8.0  "  23° 20.88" 

10° 9.16"  24° 22.18" 

11° 9.8  "  25° 23.55" 

12° 10.5  "  26° 24.98" 

13° 11.6  "  27° 26.5  " 

14° 12.0  "  28° 28.1   " 

15° 12.7  "  29° 29.78" 

16° 13.5  "  30° ....31.54" 

17° 14.4  "  31° 33.4  " 

18° 15.35"  32° 35.35" 

19° 16.3  "  33° 37.4  " 

20°  17.3  " 

PROBLEMS. 

(1)  18.2   liters  of  gas    are  measured   at   0°  C.   and 
760mm  pressure;  what  would  be  the  volume  if  measured 
at  17°  C.  and  950mm  pressure? 

(2)  A   quantity    of  oxygen   occupies    a   volume    of 
121 6CC  at  15°  C.  and  750mm  pressure;  what  is  its  volume 
under  standard  conditions? 

(3)  100  cubic  centimeters  of  hydrogen  are  measured 
off  at  27°  C.  and  950mm  pressure;  what  volume  would  it 
occupy  at  17°  C.  and  750mm  pressure? 

(4)  200CC  of  a  gas  are  measured  over  water  at  20°  C' 


22  EXPERIMENTAL  CHEMISTRY 

and  760mm  pressure;  what  volume  would  the  gas  occupy 
measured  dry  at  0°  C.  and  760mm  pressure? 


15.  (a)  Clean  a  small  piece  of  zinc,  approximately 
.05  grams,  and  weigh  accurately.  Place  it  in  a  beaker 
on  a  ring  stand,  and  introduce  a  funnel  with  the  mouth 
covering  the  zinc — stem  upward,  but  not  long  enough  to 
reach  the  mouth  of  the  beaker.  Add  water  until  the 
funnel  is  completely  covered,  and  insert  a  test  tube,  filled 
with  water,  over  the  stem;  fasten  securely  with  a  wire 
holder  or  with  a  clamp.  Then  with  a  pipette  or  a  funnel 
pour  10CC  of  concentrated  sulphuric  acid  to  the  bottom  of 
the  beaker,  and  add  a  few  drops  of  copper  sulphate  solu- 
tion. If  the  action  is  very  slow,  warm  slightly.  When 
the  zinc  has  all  been  dissolved  remove  the  clamp,  lower 
the  tube  into  the  beaker,  and  set  the  beaker  into  a  basin 
of  cold  water  and  leave  until  cold.  Raise  or  lower  the 
tube  till  the  level  of  the  liquid  is  the  same  inside  of  the 
tube  as  outside.  Why?  Cover  with  the  thumb  while  so 
adjusted,  remove  and  invert.  Let  the  gas  escape,  and 
measure  the  volume  of  the  gas.  It  is  equal  to  the  vol- 
ume of  liquid  now  required  to  fill  the  tube.  Fill  a  Bur- 
ette with  water;  take  the  reading,  and  then  run  water 
from  it  into  the  test  tube  until  it  is  exactly  as  full  as  in 
the  beginning  when  inverted  over  the  funnel.  The  dif- 
ference in  reading  gives  the  volume  of  gas.  (The 
Burette  is  read  by  noting  the  level  of  the  lower  meniscus 
of  surface.)  Read  the  thermometer  and  the  barometer  to 
get  the  temperature  and  pressure,  and  also  find  the  water 
vapor  tension  at  this  temperature.  From  these  data  cal- 
culate the  volume  dry  at  0°  C.  and  760mm  pressure. 
Hence  calculate  the  volume  of  gas  liberated  by  one  gram 


EXPERIMENTAL  CHEMISTRY  23 

of  zinc.  One  liter  (1000CC)  of  dry  hydrogen  under  stand- 
ard conditions  has  been  found  by  careful  experiment  to 
weigh  0.0896  grams  nearly.  Therefore,  calculate  the 
equivalent  of  zinc;  that  is,  the  number  of  grams  of  zinc 
required  to  yield  one  gram  of  hydrogen  from  sulphuric 
acid.  Compare  your  results  with  those  of  other  students. 

(b)  Repeat  the  above  experiment  using  hydrochloric 
acid  and  a  different  weight  of  zinc.       Is  the  final  result 
the  same? 

(c)  Repeat  the  experiment  using  .02  grams  of  mag- 
nesium,   and   sulphuric    acid.       What  is  the  equivalent 
weight  of  magnesium? 

NITROGEN. 

16.  Hollow  out  one  end  of  a  piece  of  crayon  about 
three  cm  long  and  attach  it  to  a  piece  of  wire.  Fasten 
the  wire  to  the  shelf  of  a  pneumatic  trough,  having  water 
3  or  4cm  above  the  trough.  Have  the  crayon  in  an  up- 
right position  and  of  such  a  height  that  it  will  reach 
about  half  way  to  the  bottom  of  a  large  wide-mouthed 
bottle  when  the  bottle  is  inverted  over  it.  With  a  pair  of 
forceps,  put  a  piece  of  phoshorus,  the  size  of  a  pea,  into 
the  crayon  cup.  Ignite  the  phosphorus,  and  quickly 
invert  the  wide-mouthed  bottle  over  it.  Allow  it  to  stand 
until  the  white  fumes  disappear.  What  are  these  fumes 
and  what  becomes  of  them?  Cover  the  mouth  of  the 
bottle  with  a  glass  plate,  and  turn  it  mouth  upward. 
Note  the  odor  and  color  of  the  gas.  Test  the  effect  of 
the  gas  on  a  burning  splinter,  phosphorus,  and  sulphur, 
introduced  one  after  the  other.  Does  nitrogen  support 
combustion?  Where  did  it  come  from? 

THE   ATMOSPHERE. 

The   air   is   a   mechanical   mixture,    of   which    over 


24  EXPERIMENTAL  CHEMISTRY 

ninety-nine  per  cent,  is  oxygen  and  nitrogen.*  Water 
vapor  and  carbon  dioxide  are  always  found  present  in 
varying  proportions.  Besides  these,  ammonia  and  some 
other  gases  are  usually  found  in  small  quantities. 

17.  (a)     Take   a  piece  of  glass  tubing    about    20cm 
long,  closed  at  one  end,  and  from  10  to  15mm  in  diameter. 
Bend  the  closed  end  to  a  right  angle  making  the  bend 
about  5cm  long.       Slip  two  small  rubber  rings  over  the 
open  end,  and  drop  a  piece  of  phosphorus  the  size  of  a 
pea   into   the  bent  portion.      Dip   the  open   end  into    a 
beaker   of  water,   and  suck  air  out  with  a  rubber  tube 
until  the  wrater  rises  about  3cm  in  the  tube.       Adjust  the 
tube  until  the  water  is  at  the  same  level  inside  and  out- 
side.   Why?  Mark  the  mean  level  by  the  lower  rubber  ring, 
and  fasten  the  tube  securely  with  a  clamp.       Warm  the 
closed  end  containing  the  phosphorus,  but  not  enough  to 
drive  the  expanded  air  out  of  the  tube.       I^et  the  tube 
cool  after  the  phosphorus  has  entirely  ceased  to  act.    Pour 
water  over  the  tube;  and  after  the  white  fumes  have  dis- 
appeared,   adjust  the  upper  rubber  ring  to  indicate  the 
volume  of  the  gas  left.     Is  the  volume  of  the  gas  greater 
or  less  than  that  of  the  original  air?     Why? 

(b)  Fill  the  tube,  first  to  one  rubber  ring  and  then 
to  the  other,  with  water  from  a  Burette,  and  note  the  vol- 
ume in  each  case.  Calculate  the  percentage  composition 
of  air  by  volume,  assuming  it  to  be  composed  entirely  of 
oxygen  and  nitrogen.  What  previous  experiment  showed 
the  presence  of  moisture  in  the  atmosphere? 

AMMONIA. 

18.  (a)     Add  a  few  drops  of  caustic  soda  solution 

*  In  the  year  1894;  Raleigh  and  Ramsay  discovered  that  about  1  per  cent, 
of  what  was  supposed  to  be  nitrogen  was  really  a  new  element  which  they 
called  Argon,  meaning  inert  substance.  Since  then  other  elements  have  been 
found  in  very  small  quantities. 


EXPERIMENTAL  CHEMISTRY  25 

to  a  little  ammonium  chloride  in  a  test  tube,  warm  and 
notice  the  odor  of  the  gas  given  off.  Repeat  the  opera- 
tion using  caustic  potash  instead  of  caustic  soda. 

(b)  Mix  in  a  mortar  about  a  gram  of  quicklime  and 
a  gram  of  ammonium  chloride,  and  note  the  odor  as  before. 
What  kind  of  an  odor  has  ammonia?     By  what  other  name 
is  it  commonly  known?     Write  equations  representing  the 
reactions  that  took  place  in  each  case.      (The  student  is 
supposed   to    have  had,   by  this  time,   some  practice  in 
writing  equations.) 

(c)  Mix  thoroughly  about  25  grams  of  slaked  lime 
with  an  equal  weight  of  ammonium  chloride.     Place  the 
mixture  in  a  flask  and  attach  a  delivery  tube.     Heat  the 
flask  gently  in  a  sand  bath  or  over  asbestos,  and  collect 
three  cylinders  of  the  gas  by  the  displacement  of  air; 
cover  securely  with  glass  plates.      The  mouths   of  the 
receivers     should     be    kept   downward   throughout   the 
experiment  unless  otherwise  directed,   as  the  gas  is  very 
much  lighter  than  air.     Try  to  light  the  gas  as  it  escapes 
from  the  generator.      Will  ammonia  burn?     Allow  the 
current  of  gas  from  the  generator  to  pass  into  a  beaker  of 
water  while  the  cylinders  of  gas  are  being  examined. 

(d)  Note  the  odor  and  color  of  the  gas.     Into  one  of 
the  receivers  put  a  piece  each  of  wet  blue,   and  red  litmus 
paper.     What  change  takes  place?     Introduce  a  burning 
candle  or  splinter  into  the  same   receiver.     Does  the  gas 
support  combustion?     Invert  one  of  the  cylinders  with  its 
mouth  upward,  remove  the  glass  cover,  and  quickly  apply 
a  lighted  match.     Does  the  ammonia  burn? 

(e)  Moisten  the  sides  of  a  dry  cylinder  with  concen- 
trated hydrochloric  acid,  and  place  it  over  the  third  cyl- 
inder of  the  gas  collected,  so  that  the  mouths  of  the  two 
vessels    are    separated    only   by   the    glass     cover    over 


26  EXPERIMENTAL  CHEMISTRY 

the  receiver  of  gas.     Remove  the  glass  plate,  and  observe 
carefully  what  takes  place.     What  is  formed? 

(f)  Examine  the  water  into  which  the  gas  has  been 
passing.  How  does  it  affect  litmus  paper?  Boil  some  of 
the  solution  in  a  test  tube.  What  gas  is  given  off?  How 
does  the  solution  compare  with  the  laboratory  reagent? 
The  ammonia  gas  should  be  passed  through  a  cylinder  of 
quicklime  or  caustic  soda  to  obtain  it  perfectly  dry.  Why 
could  not  calcium  chloride  be  used? 


NITROUS    OXIDE. 

19.  (a)  Place  15  to  20  grams  of  ammonium  nitrate 
in  a  retort  or  generating  flask,  and  arrange  the  apparatus 
as  in  the  preparation  of  oxygen.  Heat  gently,  and  after 
the  air  has  been  expelled,  collect  three  receivers  of  the  gas 
over  warm  water.  Nitrous  oxide  is  somewhat  soluble  in 
cold  wrater.  If  the  flask  is  heated  too  fast,  some  nitric 
oxide  will  be  formed  which  takes  oxygen  from  the  air  to 
form  nitrogen  peroxide,  No.,.  Nitrous  oxide  may  contain 
some  chlorine  also.  In  order  to  obtain  the  gas  pure,  it  is 
usually  passed  through  two  Wolff's  bottles, — the  first 
containing  a  warm  solution  of  ferrous  sulphate  which 
removes  the  nitric  oxide;  the  other,  containing  a  warm 
solution  of  caustic  potash  to  remove  the  chlorine. 

(b)  Note  the  odor,  color,  and  taste  of  the  gas.  Intro- 
duce a  lighted  splinter  into  one  of  the  receivers.  Does 
the  gas  support  combustion?  Put  a  small  piece  of  phos- 
phorus in  a  deflagrating  spoon,. ignite,  and  introduce  into 
a  second  receiver  of  the  gas.  Introduce  burning  sulphur 
into  the  third  receiver.  What  gas  does  nitrogen  monox- 
ide resemble? 


EXPERIMENTAL  CHEMISTRY  27 

NITRIC   OXIDE. 

20.  (a)     Arrange  a  generating  flask,  and  place  in  it 
a  quantity  of  metallic  copper.     J*ust  cover  the  copper  with 
water,    and   then   slowly    pour  concentrated   nitric  acid 
through  the  funnel  tube  until  action  begins.     What  is  the 
color  of  the  gas  in  the  flask  at   first?     What  is  the  color 
after  action  has  continued  for  a  short  time?     Collect  four 
cylinders   of  the  gas  over  water,   and  observe  the  color. 
Allow  the  nitric  oxide  from  the  delivery  tube  to  escape 
into  the  air  and  notice  the  change.     The  gas  unites  with 
the  oxygen  of  the  air  to  form  nitrogen  peroxide.     Explain 
the  appearance  of  the  colored  gas  in  the  flask  at  the  begin- 
ning of  the  experiment. 

(b)  Introduce  a  lighted  splinter  into  one  of  the  cyl- 
inders of  gas.     Does  the  gas  support  combustion?     Does 
it  burn? 

(c)  Put  a  small  piece  of  phosphorus  into  a  deflagrat- 
ing   spoon,    ignite,    and   lower   into  a  cylinder  of  gas. 
What  is  the  effect? 

(d)  Repeat  (c)  using  sulphur  instead  of  phosphorus. 

NITRIC    ACID.     , 

21.  Place  in  a  retort  30  grams  of  sodium  nitrate  or 
potassium  nitrate,  and  about  20CC  concentrated  sulphuric 
acid.     Pass  the  end  of  the  retort  into  the  neck  of  a  flask, 
and  arrange  so  that  the  flask  may  be  surrounded  with  ice, 
or  so  that  a  stream  of  water  may  continually  flow  over  it, 
(a  large  test  tube  may  be  used  instead  of  the  flask.     It 
can  be  kept  cool  by  immersing  in  cold  water. )     Heat  the 
retort   gently    until  the  operation  is  finished.     In  what 
form  is   the  nitric  acid?      What   is  its  odor  and  color? 
When  pure  it  is  colorless,  but  it  usually  contains  some  of 
the  oxides  of  nitrogen  which  give  it  a  yellowish  color. 


28  EXPERIMENTAL  CHEMISTRY 

(b)  Add  a  small  amount  of  nitric  acid  to  4  or  5CC  of 
indigo  solution  in  a  test  tube,  and  warm. 

(c)  Put  about  20CC  of  dilute  nitric  acid  in  an  evapor- 
ating dish,  and  drop  into  it  some  quill  clippings  or  small 
pieces  of  silk.     Evaporate.     What  color  is  imparted  to 
animal  substances? 

(d)  Test  the  action  of  nitric  acid,  both  the  concen- 
trated and  the  dilute,  (one  volume  of  concentrated  acid  to 
three  of  water)    upon  the  following  substances:  copper, 
zinc,  tin,  lead,  iron  and  magnesium.     Put  about  5CC  of  acid 
into  a  test  tube  and  then  drop  in  a  small  piece  of  the  metal 
to  be  tested.     It  is  well  to  arrange  as  many  test  tubes  as 
there  are  metals,  and  test  all   at  the  same  time.     Do  all 
the  metals  dissolve  ?     Which  one  seems  to  dissolve  most 
readily?     In  which  acid,  concentrated  or  dilute,  is  action 
most  violent? 

(e)  Put  2CC  of  concentrated  nitric  acid  into  a  test  tube 
and  drop  into  it  a  small  piece  of  platinum.     Warm  in  a 
flame,  and  notice  carefully  for  any  change. 

(f)  Repeat  (e)  using  3CC  of  concentrated  hydrochloric 
acid  instead  of  the  nitric. 

(g)  Unite  the  two  acids  used  in  (e)  and  (f).      What 
is  the  effect?     A  combination  of  the  two  acids  form  Aqua 
Regia.     The  odor  produced  is  that  of  chlorine.     The  nas- 
cent chlorine  unites  with  the  platinum  and  platinum  chlor- 
ide is  produced.     If  gold  is  used,  auric  chloride  is  formed. 

HYDROCHLORIC    ACID. 

22  (a)  Put  50  grams  of  common  salt  in  a  flask  and 
attach  a  delivery  tube.  Insert  a  thistle,  or  funnel  tube, 
and  add  about  75CC  of  dilute  sulphuric  acid.  Connect  the 
delivery  tube  to  a  series  of  two  or  three  Wolff's  bottles 
about  half  full  of  water.  Heat  the  flask  gently  over  asbes- 


EXPERIMENTAL  CHEMISTRY  29 

tos  or  in  a  sand  bath.  When  the  air  has  been  displaced, 
the  gas  will  be  absorbed  as  soon  as  it  comes  in  contact 
with  the  water.  Write  the  equation  which  shows  the 
reaction  that  takes  place.  After  the  gas  has  passed  for 
fifteen  to  twenty  minutes,  disconnect  the  flask  from  the 
Wolff's  bottles.  What  do  you  notice?  Blow  your  breath 
on  the  escaping  gas.  What  effect  has  this?  Why?  Try 
to  light  the  gas  at  the  end  of  the  tube.  Will  it  burn? 

(b)  Fill  two  wide-mouthed  bottles  with  hydrochloric 
acid  gas  by  extending  the  delivery  tube  to  the  bottom  of 
the  bottle  which  should  be  loosely  covered  with   a  glass 
plate  or  a  piece  of  cardboard.      Note  the  color  of  the  gas. 
Is  it  transparent?     Drop  a  moist  piece  of  blue  litmus  paper 
into  one  of  the  bottles.     What  is  the  nature  of  the  gas? 
Insert  a  burning  splinter  or  a  candle  into  the   bottle. 
Does  the  gas  support  combustion? 

(c)  Take  the  second  bottle  of  gas,  hold  the  glass  cover 
securely,  and  invert  the  bottle  bringing  the  mouth  under 
water  in  a  beaker  or  evaporating  dish.     Remove  the  glass 
plate.     What  happens?     Explain.     Test   the  water  with 
blue  litmus.     Taste  the  water.     Why  cannot  this  gas  be 
collected  over  water  like   hydrogen  and  oxygen?     Why 
was  it  not  necessary  to  invert  the  bottles  when  collecting 
the  gas? 

(d)  Examine  the  liquid  in  the  first  Wolff's  bottle. 
How  does  it  affect  litmus  paper?     Put  about  a  gram  of 
granulated  zinc  into  a  test  tube  and  add  about  10CC  of  the 
liquid.     What   is   the   effect?     What   gas   is   given    off? 
Compare  the  liquid  with  the  laboratory  hydrochloric  acid. 
Are  they  the  same? 

Hydrobromic  acid  and  hydriodic  acid  are  very  much 
like  hydrochloric  acid,  and  are  made  in  the  same  way. 
Give  the  equations  representing  their  preparation. 


30  EXPERIMENTAL  CHEMISTRY 

CHLORINE. 

23.     This  experiment  should  be  performed  in  the  hood 
or  out  of  doors.     Be  careful  not  to  inhale  the  gas  given  off. 

(a)  Arrange  a  flask  like  the  one  used  in  the  last 
experiment,  and  put  in  it  about  30  grams  of  manganese 
dioxide.     Pour   through  the  funnel  tube   about  50CC  of 
hydrochloric  acid — enough  to  cover  the  manganese  diox- 
ide  completely.     Heat    the   flask   gently    as  in  the   last 
experiment,  and  fill  six  cylinders  or  wide-mouthed  bottles 
with  the  gas  by  downward  displacement  of  the  air.     As  the 
chlorine  gas  collects,  the  quantity  can  be  noted  by  means 
of  the  color.     What  is  the  color?     Write  the  equation 
representing  the  action.      (Sulphuric  acid  could  be  used 
instead  of  hydrochloric  acid  if  an  equal  weight  of  common 
salt   be   added   to   the   manganese   dioxide.     Write   the 
equation).     After  the  bottles  are  full,  try  to  light  the  gas 
escaping  from  the  generator.     Will  it  burn?     Allow  the 
escaping  gas  to  run  into  a  receiver  of  water  while  you  are 
testing  the  gas  collected  in  the  wide-wouthed  bottles.     Is 
the  gas  soluble  in  water?     What  is  the  color  of  chlorine 
water?     Save  the  solution.     Pour  it  into  a  bottle,  cork, 
and  set  in  a  place  protected  from  bright  light. 

(b)  1.     Into  one  of  the  vessels  containing  chlorine 
put  some  pieces  of  red  and  blue  litmus  paper;  a  red  rose; 
a  green  leaf;  a  piece  of  cotton  print;  a  piece  of  newspa- 
per; and  a  piece  of  paper  with  some  writing  on  it.       The 
substances  used  must  be  moist.     Use  two  vessels  of  chlor- 
ine if  necessary. 

2.  Put  some  of  the  dry  articles  into  another  receiver 
of  chlorine.     In  a  short  time  examine  the  substances  in 
the  receivers,  and  observe  the  effect  upon  each. 

3.  I/ower  a  lighted  candle  or  taper  into  a  receiver  of 
chlorine.     Does  the  gas  support  combustion? 


EXPERIMENTAL  CHEMISTRY  31 

4.  Warm  a  little  oil  of  turpentine  in  an  evaporating 
dish,  moisten  a  piece  of  filter  paper  or  blotting  paper  with 
it,   and  quickly  introduce  into    a    receiver    of    chlorine. 
Observe  what  happens. 

5.  Sprinkle  into  another  receiver  of  chlorine  a  little 
finely  powdered  copper,  antimony,  or  arsenic;  and  observe 
the  effect. 

6.  Arrange  a  hydrogen  generator  as  in  experiment 
7.     (Observe  the  caution).     When  the  air  has   all  been 
expelled,  light  the  hydrogen  and  bring  the  burning  jet 
into  the  remaining  receiver  of  chlorine.     Does  it  continue 
to  burn?     What  is  formed? 

(c)  Put  about  5CC  of  indigo  solution  into  a  test  tube 
and  add  5CC  of  chlorine  water.  Do  you  notice  any  change? 
Treat  in  the  same  way  5CC  of  potassium  bichromate  solu- 
tion. Note — Teachers  should  explain,  as  far  as  possible, 
the  changes  which  take  place  in  this  experiment. 

The  preparation  of  bromine  and  iodine  is  similar  to  the 
preparation  of  chlorine.  The  apparatus  used  is  the  same 
as  that  used  in  the  preparation  of  nitric  acid.'  The  bro- 
mine condenses  in  the  receiver,  and  forms  a  reddish  liquid. 
Iodine  forms  a  sublimate  of  a  violet  color.  Write  equa- 
tions illustrating  the  reactions  that  take  place  when  bro- 
mine and  iodine  are  made. 

CARBON. 

24.  (a)  Hold  a  plate  or  piece  of  porcelain  in  the 
flame  of  a  candle,  or  of  a  Bunsen  burner  with  the  air 
supply  shut  off.  Observe  the  color  of  the  deposit.  This 
is  an  impure  form  of  carbon.  What  name  is  given  to 
this  particular  form  of  the  element?  Hold  the  deposit  in 
the  flame  of  an  alcohol  lamp,  or  in  a  Bunsen  flame  with 
the  valve  at  the  base  of  the  burner  open.  Does  the 
deposit  disappear?  Is  carbon  a  combustible  element? 


32  EXPERIMENTAL  CHEMISTRY 

(b)  Put  some  pieces  of  wood  into  a  small  Hessian  cru- 
cible and  cover  them  with  sand.  Heat  the  crucible  strongly, 
and  when  smoking  stops,  cool,  remove  the  contents,   and 
examine.       This  is  impure  carbon  also.       What  name  is 
given  to  it?       What  became  of  the  other  products  of  the 
wood?     Name  other  forms  of  the  element  carbon. 

(c)  Put  about  2  grams    of    sugar   into   a   porcelain 
evaporating  dish  and  heat  till  the  sugar  is  black.     Sugar 
is    composed    of  the    elements    carbon,    hydrogen,   and 
oxygen;  when  the  sugar  is  heated,  water  passes  off  arid 
the  carbon  is  left.       The  carbon  can  be  removed  from  the 
evaporating    dish    with    a    strong    solution    of  sodium 
hydrate. 

(d)  Place  a  few  grains  of  sugar  into  an  evaporating 
dish,  and  add  a  few  drops  of  concentrated  sulphuric  acid. 
What  results?     Try  starch  in  the  same  way. 

(e)  Test  the  solubility  of  carbon  (use   charcoal)  in 
water,  acids,  alkalies  and  alcohol. 

(f)  Heat  some  powdered  charcoal  on  a  piece  of  plat- 
inum foil.     What  occurs? 

25.  (a)  Arrange  a  bone-black  filter  by  placing  a 
paper  filter  into  a  funnel  and  adding  bone-black.  Filter 
a  dilute  solution  of  indigo  and  examine  the  filtrate.  Is 
there  any  change  in  the  appearance  of  the  solution?  Fil- 
ter in  the  same  way  a  dilute  solution  of  litmus. 

(b)  The   same   effect  may   be  produced   by  putting 
bone-black  into  the  solution,  boiling  for  a  short  time,  and 
then  filtering  through  a  paper  filter.       Try  this  with  any 
solution  colored  with  animal  or  vegetable  coloring  matter; 
as  cochineal,  indigo,  litmus,  iodine.     Take  about  50CC  in 
a  beaker  and  place  in  it  about  one  or  two  grams  of  bone- 
black;  heat  for  a  short  time,  shake  well  and  filter. 

(c)  Pour  10  or  15CC  of  hydrogen   sulphide    solution 


EXPERIMENTAL  CHEMISTRY  33 

into  a  beaker,  and  note  the  odor.  Add  about  a  gram  of 
bone-black;  warm  the  solution  a  few  moments,  shake  well 
and  filter.  Note  the  odor  again. 

(d)  Collect  over  mercury  in  a  test  tube  some  ammonia 
gas,  made  by  heating  a  strong  solution  of  ammonia  and 
passing   it  over  quick-lime  to  dry  it.     Heat   a  piece    of 
charcoal;  and,  without  removing  the  inverted  receiver  of 
gas,  press  it  through  the  mercury  into  the  mouth  of  the 
receiver.       What  is  the  result?       Why  was  the  charcoal 
heated  before  introducing  it  into  the  test  tube? 

(e)  Mix  together  3  or  4  grams  of  powdered  copper 
oxide,  CuO,  and  about  one  gram  of  powdered  charcoal; 
heat  strongly  for  some  time  in  an  ignition  tube.       What 
remains  in  the  tube?     What  gas  is  given  off?     Write  the 
equation  which  shows  the  reaction  that  takes  place.     Is 
carbon  an  oxidizing  or  a  reducing  agent?     (The  gas  given 
off  may  be  collected  by  attaching  a  delivery  tube  before 
heating  the  mixture.)       After  the  tube  has  become  cool, 
pour   in  a   little  strong   nitric  acid.     What  takes  place? 
State  some  of  the  uses  of  carbon  which  have  been  illus- 
trated by  the  experiments  you  have  performed. 

CARBON     DIOXIDK. 

26,  (a)  Put  some  small  pieces  of  marble  (calcium 
carbonate),  15  or  20  grams,  into  a  generating  flask,  and 
pour  dilute  hydrochloric  acid  on  them  through  the  funnel 
tube.  After  action  has  continued  for  a  time,  pass  the  gas 
into  a  test  tube  of  lime-water.  Is  there  any  change  in 
appearance?  Note  the  odor  and  color  of  the  gas.  Try 
to  ignite  it  as  it  escapes  from  the  delivery  tube.  Will 
carbon  dioxide  burn? 

(b)  Collect  two  or  three  cylinders  (or  bottles)  full  of 
the  gas  by  downward  displacement.  Into  one  of  the  cyl- 


34  EXPERIMENTAL  CHEMISTRY 

inders  of  gas  introduce  successively  a  lighted  candle  or 
burning  taper,  and  a  small  piece  of  phosphorus  in  a 
deflagrating  spoon.  Pour  a  cylinder  of  the  gas,  as  you 
would  water,  over  a  burning  splinter.  Does  the  gas  sup- 
port combustion?  Is  it  heavier  than  air? 

(c)  Pass  the  gas  from  the  generator  into  a  test  tube 
containing   distilled  water;  after  a  short  time,   taste  the 
water.     Test  it  with  litmus  paper. 

(d)  Pass  the  gas  for  about  ten  minutes  into  a  test  tube 
containing  a  solution  of  caustic  potash;  then  add  hydro- 
chloric  acid  to  the  solution.      What  gas    is   given    off? 
Write  equations  representing  what  has  taken  place. 

(e)  Pass   the   gas   into   clear   lime-water    as  in  the 
beginning  of  the  experiment,  but  allow  the  action  to  con- 
tinue for  a  much  longer  period.       Remove  the  delivery 
tube  and  heat  the  solution.       State  the  changes  that  you 
have  observed;  and  if  you  do  not  understand  all  of  them, 
ask  for  an  explanation. 

(f)  Blow   your  breath   through   a  clear  solution   of 
lime-water  by  means  of  a  piece  of  glass  tubing.     What  is 
formed? 

CARBON   MONOXIDK. 

27.  (a)  Put  about  ten  grams  of  oxalic  acid  crystals, 
H,C2O4,  into  a  flask;  add  about  50CC  of  concentrated  sul- 
phuric acid,  and  connect  the  flask  with  a  Wolff's  bottle 
containing  a  solution  of  caustic  soda.  Attach  a  delivery 
tube  to  the  other  neck  of  the  bottle. 

(b)  Heat  the  flask  gently  and  collect  some  of  the  gas 
in  a  test  tube  over  water.  Avoid  inhaling  the  gas  as  it  is 
poisonous.  Observe  its  color.  Try  to  set  fire  to  the  gas. 
Will  it  burn,  or  is  it  a  supporter  of  combustion?  Sul- 
phuric acid  has  great  affinity  for  water,  and  so  it  with- 
draws hydrogen  and  oxygen  from  the  oxalic  acid  in  the 


EXPERIMENTAL  CHEMISTRY  35 

right  proportion  to  form  water.  The  carbon  and  oxygen 
combine  to  form  carbon  dioxide  and  carbon  monoxide. 
What  becomes  of  the  carbon  dioxide? 

(c)  Repeat  (c)  in  Experiment  26,  using  carbon  mon- 
oxide instead  of  carbon  dioxide. 

(d)  Put  some  copper  oxide  into  a  small  hard  glass 
tube  open  at  both  ends.     Support  the  tube  in  a  horizontal 
position  and  connect  one  end  with  the  delivery  tube  from 
the  caustic  soda  solution.       Heat  the  copper  oxide  and 
pass    the    carbon  monoxide   over   it   for   a   short   time. 
Explain  the  changes  that  take  place.     Is  carbon   monox- 
ide an  oxidizing  or  a  reducing  agent? 

Problem: — How  much  carbon  monoxide  is  given  off 
by  the  decomposition  of  10  grams  of  oxalic  acid  crystals? 

FLAME. 

28.  (a)  Place  a  lighted  candle  in  front  of  some  dark 
object  and  examine  the  flame  closely.  Notice  its  shape, 
and  see  how  many  parts  you  can  distinguish.  Make 
drawings. 

(b)  Hold  a  plain  white  card,  or  piece  of  smooth  white 
pine,  horizontally  in  the  flame  of  a  candle  so  that  it  nearly 
touches  the  wick.  Remove  it  before  it  becomes  ignited 
and  hold  the  other  side  in  a  vertical  position  against  the 
wick.  Repeat  the  experiment  until  you  obtain  a  vertical 
section  and  a  transverse  section  well  outlined  on  the  card. 
Make  drawings  of  each  section.  Does  combustion  take 
place  in  all  parts  of  the  flame? 

*(c)  Light  the  gas  of  a  Bunsen  burner  and  examine 
the  flame  as  you  did  the  candle  flame  under  (a).  Has 
the  flame  the  same  number  of  parts?  Obtain  several 
small  pieces  of  soft  pine,  and  hold  them  successively  in  a 

*    Omit  sections  (c),  (d)  and  (e)  if  Bunsen  burners  are  not  used  in  the  la 


36  EXPERIMENTAL  CHEMISTRY 

horizontal  position  in  the  flame  and  try  to  determine  in 
what  part  the  combustion  is  most  complete. 

(d)  Insert  a  glass  tube  into  the  inner  cone  of  the 
Bunsen  flame;  slant  the  tube  upward,  and  apply  a  lighted 
match  to  the  upper  end.     Is  a  flame  produced?     What  is 
the  effect  of  placing  the  glass  tube  in  other  parts  of  the 
flame? 

(e)  Bring  a  piece  of  wire  gauze  down  upon  the  flame 
of  a  Bunsen  burner.     What  is  the  effect?     Is  there  any 
change  produced  after  holding  the  gauze  in  the  same  position 
for  some  time?     Turn   off  the   gas,  then  turn  it  on  again 
without  lighting;  hold   the   gauze  about  5cm  above  the 
burner  and  see  if  you  can  light  the  gas  above  it.    Explain 
all  the  phenomena  observed.     This  experiment  represents 
the  principle  upon  which  the  miner's  safety  lamp  (called 
the  Davy  safety  lamp)  is  constructed. 

(f)  Notice  which  portion  of  the  Bunsen  (or  alcohol) 
flame  is  the  most  luminous.      Sprinkle  some  drv  sawdust 
or  powdered  charcoal  in  the   flame.     Is  the  illuminating 
power  of  the  flame  greater  or  less  than  before?     Does   it 
appear  to  remain  constant?  *  Close  the  openings  at  the  base 
of  the  Bunsen  burner.     How  does  it  change  the  light  of 
the  flame?     What  are  the  openings  for?     What  seems  to 
be  the  cause  of  light  in  the  flame?      State  any  additional 
points    you   can    in    regard   to  the  combustion,  kindling 
point,  heat,  and  light  of  flame. 

SULPHUR. 

29.  (a )  What  is  the  color,  taste  and  odor  of  sulphur? 
Test  the  solubility  of  the  element  in  water,  alkalies,  acids, 
alcohol  and  carbon  bisulphide. 

(b)  Put  a  few  grams  of  sulphur  in  a  Hessian  or  por- 
celain crucible;  heat  until  the  sulphur  is  melted,  and  then 


EXPERIMENTAL  CHEMISTRY  37 

allow  it  to  cool  slowly.  As  soon  as  a  crust  forms  on  the 
surface  of  the  sulphur,  make  a  hole  through  it  and  pour 
out  the  liquid.  Examine  carefully  the  crystals  attached 
to  the  crust  and  to  the  inside  of  the  crucible.  What 
is  the  shape  of  the  crystals? 

(c)  Dissolve   one   or  two   grams   of  powdered    roll 
sulphur  in  a  little  carbon  bisulphide.       Put   the  solution 
in  an  evaporating  dish   or  beaker,   and  allow  it  to  evapo- 
rate in  the  atmosphere.     Examine  the  sulphur  crystals. 
Have  they  the  same  shape  as  those  formed  in  (b)? 

(d)  Put  in  a  retort  a  small  amount  of  sulphur,  and 
pass  the  end  of  the  retort  into  the  neck  of  a  flask.      Heat 
the   sulphur   to   boiling,   and   after   a   time  examine  the 
sulphur    that  has   collected   in   the   flask.     It   is    called 
flowers  of  sulphur. 

(e)  Put  some    sulphur   into   a   test   tube   and   heat 
slowly   till   it   melts.     Observe   the  color  of  the  liquid. 
Continue  the  heating  and  notice  carefully  any  changes  that 
take  place.     When  it  becomes  a  thin  liquid,  pour  a  little 
into  an  evaporating  dish  containing  water.     Allow    the 
heating  to  go  on  until  the  liquid  begins  to  boil,  and  then 
pour  some  more  into  cold  water. 

Sulphur  boils  at  about  450°  and  just  above  this  point 
it  takes  fire.  Take  the  two  deposits  out  of  the  water  and 
examine  them;  replace  them  in  the  water  and  after  they 
have  remained  for  some  time,  examine  again.  Do  you 
notice  any  change? 

What  is  formed  when  sulphur  burns  in  oxygen? 

SULPHUR    DIOXIDE. 

30.  (a)  Note  the  color  and  odor  of  the  substance 
formed  when  sulphur  burns  in  air. 

Put  some  pieces  of  sheet  copper  or  copper  filings  into 


38  EXPERIMENTAL  CHEMISTRY 

* 

a  generating  flask,  and  add  enough  concentrated  sulphuric 
acid  to  cover  them.  Heat  the  flask  gently  and  collect 
two  cylinders  of  the  gas  by  downward  displacement  of  the 
air.  What  is  the  color  of  the  gas?  Has  it  an  odor? 
Avoid  inhaling  much  of  the  gas. 

(b)  Introduce  a  lighted   splinter  into  the  mouth  of 
one   of  the   receivers.      Does   sulphur   dioxide   support 
combustion?     Put  some  moist  pieces  of  litmus  paper  in 
a  receiver  of  the  gas.     What  is  the  effect? 

(c)  Pass  some  of  the  gas  into  a  beaker  containing 
water.     Is  the  gas  soluble  in  water?     Kxamine  the  water 
and  test  it  with  litmus.     What  are  its  properties? 

(d)  Put  a  gram  or   two  of  sulphur  in  a  porcelain 
crucible  and  place  it  under  a  tripod  or  other  support  upon 
which  are  placed  as  many  of  the  following  things  as  may 
be  had:  moist  flowers,  green  leaves,  a  piece  of  white  woolen 
yarn,  a  ripe  apricot  (or  peach)  cut  in  halves,  a  piece  of 
moistened  unbleached  silk.     Ignite  the  sulphur  and  place 
a  large  bell-jar  over  it  so  as  to  enclose  the  articles  on  the 
tripod.         lyeave   undisturbed    until    the    fumes    settle 
and   then    examine.     What   change    takes   place  in   the 
substan  ces? 

(e)  A  solution  of  sulphur  dioxide  in  water   forms 
sulphurous  acid,  H2SO3.     If  left  in  contact  with  the  air,  it 
combines  with  oxygen   and  is  converted  into  sulphuric 
acid,    H2SO4.     It  has  the  power  of  taking  oxygen  from 
other  substances  also.     Is  it   an    oxidizing  or  a  reducing 
agent?     Add  a  little  of  the  sulphurous  acid  obtained  in  (c  ) 
to  a  solution  of  potassium  permanganate  or   potassium 
bichromate    containing    a  little   sulphuric    acid.     What 
change  is  noticeable? 


EXPERIMENTAL  CHEMISTRY  39 

V  ••*• 

HYDROGEN   SULPHIDE. 

31.  (a)  Put  a  few  pieces  of  iron  sulphide,  FeS,  in  a 
generating  flask,  and  pour  enough  dilute  sulphuric  acid 
through  the  funnel  tube  to  cover  them.  Write  the 
equation  representing  the  reaction. 

(b)  Collect  some  of  the  hydrogen  sulphide  by  the 
displacement  of  air.     Make  the  necessary  tests  to  enable 
you   to  answer  the  following  questions:  1.  What  is  its 
odor   and   color?     2.  Will   it  burn?     3.  Will   it   support 
combustion?      4.  Is  it  soluble  in  water?     5.   Is  it  acid  or 
alkaline? 

(c)  Place  in  different   test  tubes  5CC  of  each  of  the 
following  solutions:  Copper  sulphate,  CuSO4;  lead  nitrate, 
Pb(NO3)2;    mercuric   chloride,    HgCl2;  arsenic   chloride, 
AsCl3;    antimony    chloride,     SbCl3;    stannous    chloride, 
SnCl2.     Pass  some  of  the  gas  from  the  generator  into  each 
tube.     Sulphides  of  the  metals  are  formed;  note  the  color 
of  each  precipitate  and  write  the  equations  which  repre- 
sent the  reactions  that  take  place. 

(d)  Repeat   (c)    using,    instead   of  the   gas,    water 
through  which  the  gas  has  been  passed.     What  is  the 
result? 

(e)  Hydrogen  sulphide  is  thus   used   in  analytical 
operations,  and  is  a  group  reagent.     Pass  some  of  the  gas, 
or  pour  some  of  the  solution  used  in  (d)   into  5CC  of  a 
solution  of  barium  nitrate.     Is  a  precipitate  formed?    Mix 
5CC  of   the   lead   nitrate   solution   with  5CC  of  the  barium 
nitrate  solution  in  a  test  tube,  and  pass  the  gas  into  the 
liquid.     What  is  precipitated?      How  could  you  separate 
the  lead  from  the  barium? 

(f)  Pour  a  little  lead  acetate  solution    on   a   piece  of 
filter  paper  and  allow  the  gas  to  come  in  contact  with  it, 
or  pour  a  little  of  the   water  solution  over  it.     Note  the 


40  EXPERIMENTAL  CHEMISTRY 

change.      What  is  formed?      This  is  a  characteristic  test. 

SULPHURIC    ACID. 

32.  This  experiment  should  be  performed  with  the 
assistance  of  the  teacher  as  it  requires  careful  manip- 
ulation. 

(a)  Take  a  large  flask  and  insert  a  stopper  having 
five  openings.     Pass  a  delivery  tube  from  three  of  these 
openings  to  three  smaller  flasks,  and  leave  the  others  open 
to  the  air.     It  is  advisable,  when  convenient,  to  force  air 
into  the  large  flask  through  one  of  the  openings  by  means 
of  a  pair  of  bellows.     Into    one    of  the   small   flasks  put 
some  copper  turnings,  or  foil,  and  concentrated  sulphuric 
acid;  into  another  copper  turnings  or  foil  and  dilute  nitric 
acid;  into  the  third  water.     Heat  the  flasks  containing 
water,  and  sulphuric  acid  and  copper.     Notice  the  fumes 
that  pass   into  the  large  flask.     A  current  of  steam    is 
formed;  sulphur  dioxide;  and  oxides  of  nitrogen — mainly 
nitric   oxide.       These    gases    react   upon     one     another 
in  contact  with  the  air  and  form  sulphuric  acid. 

This  experiment  may  be  performed  on  a  still  smaller 
scale  by  using  test  tubes  instead  of  flasks. 

(b)  1.  Test   the   liquid   formed   with  red    and  blue 
litmus  paper.     2.   Pour  15CC  of  water  into  an  evaporating 
dish  and  add  5°°  of  concentrated  sulphuric  acid.      What 
is  the  effect  upon  the  temperature  of  the  solution?      Save 
the  dilute  acid.      3.  Take  5CC  of  the  dilute  acid  in  a  test 
tube  and  add  barium  chloride  solution,    BaCl.2.       What  is 
the  color  of  the  precipitate  formed?      What  is  it?      Write 
the  equation.     This  is  the  characteristic  test  for  sulphuric 
acid    and  soluble  sulphates.     Try  the  solubility  of  the 
precipitate  in  acids. 

4.  Put  some  wood  shavings  into  an  evaporating  dish 
and  pour  over  them  some  concentrated  sulphuric  acid. 


EXPERIMENTAL  CHEMISTRY  41 

Note  the  effect.  How  does  the  product  compare  with  the 
charcoal  formed  in  (b),  Exp.  24?  Is  there  any  analogy 
between  the  two  methods?  Which  is  the  ordinary 
method  of  preparation? 

ACIDS,     BASKS,     SALTS,     ETC. 

Acids  consist  of  hydrogen  with  a  negative  element;  i. 
e.,  a  non-metal,  (Hydracids;  as  hydrochloric,  HC1,  and 
hydrogen  sulphide,  H.,S),  or  with  oxygen  and  a  negative 
element  (Oxyacids,  as  nitric,  HNO3,  and  sulphuric, 
H.2SOJ.  Thio-acids  contain  sulphur  in  place  of  oxygen. 
Acids  generally  redden  litmus,  especially  those  which  are 
soluble — all  the  stronger  acids  are  soluble.  Anhydrides 
are  oxyacids  minus  water.  Mono-  di-  tri-  and  tetra- 
basic  acids  contain  one,  two,  three,  and  four  atoms  of 
basic  or  replaceable  hydrogen  to  the  molecule;  as,  HC1, 
H2S04>  H3PO,,  H4Si04. 

Elements  which  combine  with  hydrogen  or  hydrogen 
and  oxygen  to  form  compounds  with  acid  properties  are 
called  acid-forming  elements  or  non-metals;  such  as 
sulphur,  nitrogen,  fluorine,  chlorine,  bromine,  iodine, 
phosphorus,  arsenic,  carbon,  and  silicon. 

Metals  are  those  elements  which  combine  with 
oxygen,  or  with  oxygen  and  hydrogen,  to  form  com- 
pounds which  have  basic  properties.  They  are  called 
base-forming  elements  or  metals;  such  as  potassium, 
sodium,  calcium,  magnesium,  aluminum,  zinc,  iron,  lead, 
tin,  copper,  silver,  mercury,  platinum,  and  gold. 

Bases  (hydroxides  or  hydrates)  contain  a  metal  or 
positive  element  with  hydrogen  and  oxygen.  The 
strongest  bases  are  the  Caustic  Alkalis,  and  the  Alkaline 
Earths.  The  Caustic  Alkalis,  potassium  hydroxide, 
KOH;  sodium  hydroxide,  NaOH;  and  ammonium- 
hydroxide,  NH4OH,  are  very  soluble  in  water,  and  their 


42  EXPERIMENTAL  CHEMISTRY 

solutions  turn  litmus  blue.  The  Alkaline  Earths,  barium 
hydroxide,  Ba(OH),;  strontium  hydroxide,  Sr(OH),; 
and  Calcium  Hydroxide,  Ca(OH)2,  are  less  soluble  but 
turn  litmus  blue.  Most  other  bases  are  insoluble  in 
water  and  do  not  turn  litmus  blue. 

The  substances  formed  when  an  acid  neutralizes  a 
base  are  called  salts.  Water  is  formed  at  the  same  time. 
Besides  litmus,  other  indicators,  chiefly  organic,  as  coch- 
ineal, methyl  orange,  etc.,  may  be  used  to  distinguish 
acids  from  alkalies  by  change  of  color.  The  salts  formed 
by  neutralizing  sulphuric  acid  are  called  sulphates;  those 
formed  from  nitric  acid  are  called  nitrates;  and  those 
derived  from  hydrochloric  acid  are  called  chlorides. 

A  normal  salt  is  one  which  is  formed  by  replacing  all 
the  hydrogen  of  an  acid  with  a  metal;  as  sodium  carbon- 
ate, Na2CO3;  zinc  sulphate,  ZnSOj.  An  acid  salt  is  one 
which  is  formed  by  replacing  only  a  part  of  the  hydrogen 
of  an  acid  with  a  metal,  as  KHSO,,  and  NaHCO3.  A 
basic  salt  is  one  in  which  all  the  hydrogen  is  replaced  by 
a  metal  and  a  further  quantity  of  oxide  or  hydrate  enters 
into  the  molecule,  as  ZnSO4.  ZnO. 

33.  (a)  Evaporate  to  dry  ness  in  a  porcelain  evap- 
orating dish,  lO00  of  dilute  hydrochloric  acid,  note  the 
appearance  and  amount  of  residue. 

(b)  Repeat    (a)    with  10CC  sodium  hydrate  solution, 
NaOH. 

(c)  Take  10  to  locc  of  dilute  hydrochloric  acid  in  an 
evaporating   dish,    add  sodium    hydrate    drop    by   drop 
till  the  solution  no  longer  affects  either  red  or  blue  litmus. 
Test  by  inserting  small  bits  of  litmus  paper,  or  put  one 
or    two    drops    of    litmus     solution     into    the     liquid. 
Evaporate   to    dryness,  cool,    and  examine  the    residue. 
What  does   it  taste  like?       Dissolve   a   little    in    water. 


EXPERIMENTAL  CHEMISTRY  43 

Does  it  affect  litmus?     Write  the  equation  which  shows 
what  has  taken  place. 

(d)  Repeat   (c)  using   sulphuric    acid   and   sodium 
hydrate. 

(e)  Repeat    (c)    using    nitric    acid   and   potassium 
hydrate. 

NEUTRALIZATION. 

34.  (a)  Fasten  two  burettes  to  a  ring-stand.  Fill 
one  with  sulphuric  acid,  the  other  with  prepared  sodium 
hydrate  containing  .05  grams  of  actual  sodium  hydrate 
to  the  cubic  centimeter.  (Ask  for  the  liquids  to  be  used.) 
In  using  burettes,  if  previously  used  for  solutions  of 
different  strength  or  composition,  or  if  not  perfectly  dry 
and  clean,  rinse  well  with  water,  and  then  with  a  small 
quantity  of  the  liquid  to  be  used.  Always  fill  with  a 
clean  dry  funnel.  Read  the  level  carefully  by  the  lower 
meniscus,  before  and  after  drawing  out  the  liquid. 

(b)  Run  about  10CC  of  the  soda  solution,   noting  the 
exact   amount,    into  a   clean    beaker  standing  on  white 
paper;  add  two  or  three  drops  of  litmus  solution  for  an 
indicator,    then    run    in    acid    little  by    little,     stirring 
constantly,    till  neutral;  the   slightest   excess   of  acid  is 
indicated   by   a   faint   permanent  pink  color.     Note  the 
exact  volume  of  each  liquid  taken  and  then  determine 
the  ratio—  1:X. 

Form  of  Noting  Burette  Readings: 

Alkali  (NaOH)  Acid  (H.SOJ 

2.6  0. 

12.8  15.5 

Volume  10.2  :  15.5=1  :X.     X=1.5+ 

(c)  Rinse  the  beaker  and  redetermine  with  a  some- 
what larger  quantity  of  sodium  hydrate. 


44  EXPERIMENTAL  CHEMISTRY 

(d)  Take  about  15CC  of  the  acid  solution  in  a  clean 
beaker,    add   the   indicator,   and    then  run    in    the   soda 
solution  till  neutral  (end  of  reaction  is  disappearance  of 
pink  color).     Compare  the  value  of  X  found,   and  take 
the  mean  of  the  two  most  concordant  as  the  true  value  of 
X.      What      does     the      experiment     show     regarding 
combination    in  definite    proportions?       Write    reactions 
corresponding  to  what  has  taken  place.       As   one  cubic 
centimeter   of  sodium  hydrate  is  known  to  contain    .05 
grams  of  sodium  hydrate,  calculate:       How  many  grams 
of    sulphuric    acid   will    neutralize    lcc    of    the    sodium 
hydrate.     How  many  grams  of  sulphuric  acid  there  are 
in   lcc   of    the   sulphuric   acid   solution.       By    this    last 
calculation  you  will  standardize  the  acid  solution.       Use 
this  standard  to  determine  by  a  similar  procedure: 

(e)  What   weight  of  potassium  hydrate  there  is  in 
the    total   amount  of  test  solution    given    you    by   your 
instructor. 

Acidimetry  and  Alkalimetry  are  based  on  these 
methods  of  neutralization  (saturation);  a  known  quantity 
of  pure  acid  or  pure  alkali  being  taken  as  a  starting- 
point. 

Problem:  —  Write  the  equation  and  calculate  how 
many  grams  of  actual  sulphuric  acid  are  needed  to 
neutralize  5  grams  of  actual  sodium  hydrate.  How  much 
sodium  sulphate  wjll  be  formed? 


PART    II. 

THE    METALS    AND    THEIR    COMPOUNDS. 

« 

POTASSIUM. 

35.  (a)  (Always  handle  potassium  and  sodium 
with  forceps.) 

Cut  off  a  small  piece  of  potassium  from  one  of  the  sticks 
in  the  bottle,  and  note  the  appearance  of  the  cut  portion. 
Place  the  piece  of  potassium  on  your  ring-stand  and 
leave  exposed  to  the  air.  Note  the  changes  it  undergoes. 

(b)  Take   a   small  piece    of  potassium,  about   one- 
fourth  the   size   of  a   pea,    from    the   bottle;    and,    after 
absorbing  the  adhering  oil  with  a  filter   paper,   drop  it 
upon    the  surface  of  water  in   an  evaporating  dish.       Is 
potassium   heavier   or    lighter    than    water?       Why    is 
potassium    kept    under    oil?     Drop    a    second   piece  of 
potassium  upon  the  water  and  look  at  the  flame  through 
a  blue  glass.       What  is  the  color  of  the  flame  as  seen 
through  the  glass? 

(c)  Examine  the  water  in  the  evaporating  dish;  wet 
the  fingers  with  it;  try  its  action  on  red   litmus  paper. 
Write  the  equation  which  represents  the  reaction  that  has 
taken  place. 

(d)  Some  volatile  substances  produce  characteristic 
colors.    It  is  necessary  to  moisten  some  with  hydrochloric 
acid  or   concentrated    sulphuric    acid.      Put    some   fine 
potassium  chloride  in  a  watch  crystal  and  moisten  with 
hydrochloric  acid.     Make  a  loop  in  the  end  of  a  piece  of 


46  EXPERIMENTAL  CHEMISTRY 

platinum  wire,  and  dip  it  into  the  potassium  chloride. 
Hold  it  in  the  outer  edge  of  a  Bunsen  or  alcohol  flame 
and  observe  the  color  of  the  flame. 

(e)  Repeat  the  flame  test  using  another  potassium 
salt.  lyook  at  the  flame  through  a  blue  glass.  What  is 
its  appearance?  In  most  cases  the  platinum  wire  may  be 
dipped  into  strong  solutions  of  the  salt,  or  the  wire 
moistened  and  dipped  into  a  little  of  the  salt. 

POTASSIUM    COMPOUNDS. 

36.     (a)     The  Hydroxide. 

Dissolve  10  grams  of  potassium  carbonate  in  about 
125CC  of  water  and  boil  in  an  iron  (or  silver)  dish.  Why? 
Slowly  add  5  grams  of  slaked  lime  to  the  boiling  liquid, 
and  stir  constantly  until  all  the  lime  has  been  added. 
Allow  the  solution  to  cool  and  then  decant  off  the  clear 
liquid  into  a  bottle  and  use  when  required.  Try  its 
action  upon  litmus  paper.  In  what  other  way  has 
potassium  hydrate  been  prepared? 

(b)  How  may   potassium   sulphate,  and   potassium 
nitrate  (saltpetre)  be  made?     Review  Experiment  33. 

Most  of  the  potassium  nitrate  in  use  is  made  from 
sodium  nitrate  (chili  saltpetre)  by  treating  with  potassium 
chloride.  Write  the  equation. 

Saltpetre  or  nitre  is  used  in  the  preparation  of 
sulphuric  acid  (For  what  purpose?),  and  in  the 
preparation  of  gunpowder. 

(c)  Gunpowder. 

Mix  together  intimately  in  a  mortar  about  4  grams  of 
potassium  nitrate;  and  one  gram  of  charcoal  and 
sulphur,  using  a  little  more  charcoal  than  sulphur.  Pour 
the  powder  on  the  iron  base  of  your  ring-stand  and  set 
fire  to  it.  Potassium  nitrate  is  easily  broken  up  and 


EXPERIMENTAL  CHEMISTRY  47 

contains  enough  oxygen  for  the  combustion  of  the  mass. 
Gases,  principally  carbon  dioxide  and  nitrogen,  are 
liberated;  and,  at  the  time  of  combustion,  occupy  several 
hundred  times  the  volume  of  the  solid  powder.  Hence 
the  great  explosive  force  when  the  powder  is  confined. 

(d)  Colored  flame. 

Mix  intimately  in  a  mortar  2  grams  of  powdered  stron- 
tium nitrate;  2  grams  of  powdered  potassium  chlorate;  and 
one-half  gram  of  flowers  of  sulphur.  Set  fire  to  the 
mixture  as  before.  What  is  the  color  of  the  flame? 

(e)  Repeat    the    same     experiment    using    barium 
nitrate  instead  of  strontium   nitrate.     What  is  the  color 
of  the  flame  produced? 

SODIUM. 

37.  (a)  Bxamine  a  piece  of  metallic  sodium,  and 
leave  it  exposed  to  the  air  as  in  the  case  of  potassium. 

(b)  Throw  a  piece  of  sodium   upon  the  surface  of 
water;  and  when  it  has  disappeared,  throw  a  second  piece 
upon  the  water  and  touch  it  with  a  lighted  match.       The 
same  effect  may  be  produced  by  throwing  the  sodium  upon 
hot  water.     Try  it.     How  does  the  action  of  sodium  upon 
water  differ  from  the  action  of  potassium  upon  water? 

(c)  Repeat   (d)    and     (e)    Experiment    35,     using 
sodium  salts  instead  of  potassium   salts.     What  is   the 
color  of  the  flame?     What  effect  has  the  blue  glass? 

(d)  Try  a  mixture  of  a  sodium  salt  and  a  potassium 
salt.     What  is  the  color  of  the  flame?     Could  you  detect 
the  presence  of  potassium  in  the  mixture  by  looking  at 
the  flame? 

lyook  at  the  flame  through  the  blue  glass.  What  is  the 
appearance  of  the  flame?  How  could  you  distinguish 
between  potassium  and  sodium  compounds? 


48  EXPERIMENTAL  CHEMISTRY 

(e)  Examine  a  number  of  sodium  compounds  as  to 
color  and  solubility  in  water. 

(f)  Compare  briefly  the  properties  of  potassium  and 
its   compounds   with   the   properties   of  sodium    and    its 
compounds. 

SODIUM     COMPOUNDS. 

38.  (a)  How  may  the  following  sodium  compounds 
be  prepared?  Sodium  chloride,  sodium  sulphate,  and 
sodium  nitrate.  See  Kxp.  33.  Sodium  chloride  is 
obtained  in  large  quantities  from  sea  water.  How?  The 
preparation  of  sodium  hydroxide  is  similar  to  that  of 
potassium  hydroxide.  Write  the  equation. 

(b)  Sodium  carbonate.  (Solvay  or  ammonia 
process. ) 

Take  about  2-r)cc  of  ammonia  solution  and  pass  carbon 
dioxide  from  a  generator  into  it  until  the  carbon  dioxide 
is  no  longer  absorbed.  A  solution  of  acid  ammonium 
carbonate  is  formed. 

NH4OH+CO2=HNH4CO8. 

Slowly  add  to  this  a  strong  solution  of  sodium 
chloride  as  long  as  a  precipitate  is  formed.  This  is 
monosodium  carbonate,  which  is  comparatively  difficultly 
soluble  in  water. 

HNH4CO3-fNaCl=HNaCO3-fNH4Cl. 

What  is  left  in  solution? 

Filter  the  precipitate  and  dry  in  an  oven.  (It  may  be 
partially  dried  by  pressing  between  filter  papers.) 

Transfer  the  precipitate  to  a  crucible  or  ignition  tube, 
and  heat  until  carbon  dioxide  is  no  longer  given  off.  The 
residue  is  sodium  carbonate. 

2HNaCOs=NaiCO,-fCOa+H20. 

Put  some  of  the  residue  in  a  test  tube  and  add  a  little 


EXPERIMENTAL  CHEMISTRY  49 

dilute  hydrochloric  acid.  What  is  given  off?  Determine 
the  presence  of  the  metal  by  the  flame  test.  What  is 
the  color  of  the  flame? 

AMMONIUM    COMPOUNDS. 

39.  (a)  Ammonium  is  a  hypothetical  metal,  being 
too  unstable  to  exist  alone. 

Review  the  experiments  on  ammonia.  What  does 
ammonia  gas  dissolved  in  water  form?  How  does  it  affect 
litmus  paper?  Name  a  characteristic  test  for  ammonia. 
See  (a)  Experiment  18. 

(b)  Examine    a    number     of   the     compounds     of 
ammonium  as  to  color  and  solubility  in  water.     How  do 
they  compare  with  potassium  and  sodium  compounds  in 
these  respects?     Do  ammonium  salts  give  a  characteristic 
flame. 

Always  have  your  platinum  wire  clean  before  trying 
the  flame  test.  Clean  the  wire  by  dipping  it  into  hydro- 
chloric acid  and  igniting.  Sometimes  it  is  necessary  to 
scrape  the  wire  slightly  with  a  knife. 

(c)  Ammonium  sulphide. 

Take  50CC  of  a  comparatively  strong  solution  of 
ammonia,  and  divide  it  into  two  parts  of  about  25CC  each. 
Pass  hydrogen  sulphide  from  a  generator  into  one  part 
until  the  solution  is  saturated.  A  characteristic  odor  will 
be  noted  when  the  solution  is  near  saturation. 

The  product  is  a  solution  of  ammonium  hydrosul- 
phide.  Add  to  this  the  other  part  of  the  ammonia 
solution  and  ammonium  sulphide  will  be  formed.  Note 
the  odor  and  color  of  the  liquid.  Pour  it  into  a  bottle  and 
cork  securely. 

Ammonium  sulphide  is  a  group  reagent  and  is  used 
to  precipitate  those  sulphides  which  are  soluble  in  dilute 


50  EXPERIMENTAL  CHEMISTRY 

hydrochloric  acid.  Take  two  test  tubes  containing  two 
or  three  cubic  centimeters  of  zinc  sulphate  solution. 
Pour  a  little  hydrochloric  acid  into  each  test  tube.  Is  a 
precipitate  formed? 

Add  a  few  drops  of  hydrogen  sulphide  solution  to  one 
and  a  few  drops  of  ammonium  sulphide  to  the  other. 
What  are  the  results? 

Repeat  the  tests  using  cobaltous  chloride  instead  of 
zinc  sulphate. 

(d)     How  are  the  following  compounds  formed: — 

Ammonium  chloride,  ammonium  nitrate,  and  ammo- 
nium sulphate? 

Write  the  equations. 

CALCIUM    COMPOUNDS. 

40.  The  element,  calcium,  is  not  found  uncombined. 
It  has  no  practical  application,  hence  it  is  not  made  in  any 
considerable  quantity. 

(a)     Calcium  Hydrate. 

Put  10  grams  of  quicklime  (calcium  oxide)  in  an 
evaporating  dish  and  slowly  add  about  20CC  of  water  to  it. 
Observe  what  takes  place.  Slaked  lime  (calcium  hydrate) 
is  formed,  and  the  process  is  called  slaking. 

Add  300  or  400°°  of  water  to  the  slaked  lime  and  pour 
the  whole  into  a  bottle  and  cork  securely.  Examine  it 
the  next  laboratory  hour.  Has  any  of  the  lime  dissolved? 
Test  some  of  the  clear  solution  with  litmus  paper.  Is 
there  any  change?  The  solution  is  known  as  lime-water. 
It  may  be  poured  from  your  bottle  into  the  bottle  labeled 
"  Lime-  water." 

What  takes  place  when  you  blow  your  breath  through 
clear  lime-water?  What  change  does  it  undergo  when 
exposed  to  the  air?  Review  (a)  and  (f)  Experiment  26. 


EXPERIMENTAL  CHEMISTRY  51 

Add  lime-water  to  a  solution  of  ferric  chloride.  Fer- 
ric hydroxide  is  thrown  down.  What  is  its  color? 

Add  a  little  sulphuric  acid  to  lime-water.  What  is 
formed? 

(b)  Calcium  sulphate  (gypsum). 

Heat  some  powdered  gypsum  in  an  ignition  tube. 
Does  it  contain  water  of  crystallization? 

Put  4  or  5  grams  of  gypsum  in  a  crucible  and  heat 
for  twenty  or  thirty  minutes  in  an  air  bath  or  over  a 
flame  at  about  150° — avoid  heating  above  200°. 

Add  enough  water  to  the  residue  to  form  a  paste  and 
allow  it  to  stand.  Moisten  some  gypsum  that  hks  not 
been  heated  and  allow  it  to  stand  for  a  time.  Is  there  any 
difference  between  the  two?  Gypsum  heated  in  this  way 
forms  a  powder  known  as  plaster  of  Paris. 

(c)  Take  the  carbonate,   the  chloride,   and  the  sul- 
phate of  calcium  and  try  their  solubility  in  water,  in  acids 
(hydrochloric  and  nitric),  and  in  alcohol. 

What  has  calcium  chloride  been  used  for  in  previous 
experiments?  Water  containing  calcium  carbonate,  or 
water  containing  calcium  sulphate  in  solution,  is  called 
a  hard  water.  The  former,  temporarily  hard  because 
the  hardness  is  easily  removed  by  boiling;  the  latter, 
permanently  hard  because  the  hardness  is  not  removed 
by  boiling. 

(d)  Take  a  little  calcium  chloride  and  see  what  color 
it  gives  to  the  flame.     Compare  it  with  sodium. 

What  tests  would  you  employ  to  distinguish  between 
the  chlorides  of  potassium,  sodium,  ammonium,  and 
calcium? 

ZINC. 

41.  (a)  Examine  some  metallic  zinc.  What  is  its 
color?  What  effect  has  the  common  acids  (hydrochloric, 


52  EXPERIMENTAL  CHEMISTRY 

sulphuric  and  nitric)   upon  ordinary  zinc?     What  gas  is 
usually  evolved? 

Try  the  effect  of  caustic  alkalies  upon  zinc.  See  if 
you  can  write  the  equations  expressing  the  reactions. 

For   what   purpose    has   zinc   been   previously  used? 
Mention  any  uses  of  zinc  with  which  you  are  familiar. 
What  is  the  equivalent  weight  of  zinc? 

(b)  Heat  a  small  piece  of  zinc  on  charcoal  in  the 
reducing  flame.  Does  the  zinc  burn?  What  is  the  resi- 
due formed? 

Note  the  color  of  the  sublimate  while  hot  and  when 
cold?  When  it  becomes  cool  moisten  with  dilute  cobalt 
nitrate  and  heat  again.  What  is  the  color  of  the 
sublimate? 

ZINC    COMPOUNDS. 

42.  (a)  Examine  several  of  the  compounds  of  zinc. 
What  is  their  usual  color? 

(b)  Take  four  test  tubes  and  pour  into  each   about 
5°°  of  zinc   sulphate   solution.     Add   to   one  of  these  a 
solution  of  potassium  hydroxide;  to  another,  a  solution  of 
sodium    carbonate;    to   the   third,     ammonium    hydrate 
solution;  and   to   the   fourth,    a  solution  of  ammonium 
sulphide.     Give  the  colors  of  the  precipitates.     Write  the 
equations  to  show  what  is  formed  in  each  case.     Under- 
line the  parts  which  represent  the  precipitates. 

(c)  Take  the  test  tube  in  which  you  added  potassium 
hydroxide,  and  add  an  excess  of  the  reagent.     What  is 
the  effect?     Divide  the  solution   into  two  parts.      Dilute 
one  part,  and  boil  the  other.     What  are  the  results? 

OXIDATION   AND   REDUCTION. 

Oxidation  takes  place  when  oxygen  or  any 
negative  element  or  group  is  added  to  an  element  or 


EXPERIMENTAL  CHEMISTRY  53 

compound,  and  when  hydrogen  or  any  positive  element 
or  group  is  removed — it  consists  in  the  increase  of  the 
proportion  of  the  more  negative  constituents. 

Reduction  takes  place  when  oxygen  or  any  negative 
element  or  group  is  removed  from  a  compound,  or  when 
hydrogen  or  any  positive  element  or  group  is  added — it 
is  the  reverse  of  oxidation. 

The  valence  of  an  element  (monad,  dyad,  triad,  etc. ) 
is  the  number  of  bonds  or  units  of  chemical  force  it 
possesses.  It  is  measured  by  the  number  of  atoms  of 
hydrogen  or  chlorine  which  one  of  its  atoms  combines 
with  or  replaces.  Oxidation  or  reduction  takes  place 
when  the  number  of  acting  bonds  of  an  atom  of  any 
element  suffers  change. 

The  following  are  the  principal  elements  which  form 
two  series  of  salts:  —  Iron,  mercury,  tin,  antimony, 
arsenic,  manganese,  and  copper.  By  suitable  means,  the 
lower  (ous)  salts  of  each  can  be  converted  into  the  higher 
(ic)  salts  and  vice  versa. 

In  the  following  experiments  on  oxidation  and 
reduction,  use  very  small  quantities  of  the  substances 
called  for,  and  have  the  vessels  you  use  well  cleaned. 
Notice  carefully  the  nature  of  each  reaction. 

43.  (a)  Burn  a  little  sulphur  in  air.  What  is 
formed?  Has  oxidation  or  reduction  taken  place? 

(b)  Put  a  little  finely  powdered  sulphur  in  a  test 
tube  and  add  about  5CC  of  nitric  acid.  Warm  for  about 
ten  minutes.  Part  of  the  sulphur  is  oxidized  to  SO3. 

S4-2HNO3=H2SO4-f2NO. 

Test  the  presence  of  sulphuric  acid  by  diluting  the 
solution  to  four  or  five  volumes  and  adding  barium 
chloride.  A  white  precipitate,  insoluble  in  acids, 
indicates  a  sulphate.  Write  the  equation. 


54  EXPERIMENTAL  CHEMISTRY 

(c)  Place  a  drop  or  two  of  mercuric  chloride  solution 
on  a  clean  piece  of  copper  or  zinc.       It  is  reduced  finally 
to  metallic  mercury.     Write  the  equation.       What  is  the 
nature  of  the  change  in  the  nitric  acid  in  (b),  and  of  the 
zinc  or  copper  in  (c)? 

(d)  Take  5CC  of  mercuric  chloride,  HgCl.,,    in  a  test 
tube,   and   add    one   or  two  drops  of  stannous  chloride, 
SnCl2;  warm  and  note  the  result.    Now  add  a  considerable 
amount  of  stannous  chloride,  heat  and  observe  the  result 
as  before.      Stannic  chloride,  SnCl4,    is    formed    in  each 
case;  in  the  first  mercurous  chloride,   Hg2Cl,,  and  in  the 
second  mercury  is  precipitated. 

(1)  2HgCl24SnCli=Hg2Cl2-fSnCl4. 

(2)  HgCl2+SnCl2=Hg-fSnCl4. 

(e)  Put  a  small  globule  of  mercury  in  a  test  tube, 
and  add  5CC  of  dilute  (diluted  5  to  1 )  nitric  acid.     Warm 
very  gently  for  a  few  minutes,  if  necessary  to  produce 
action.     Mercurous  nitrate  is  formed.       Test  the  liquid 
with  a  few  drops  of  hydrochloric  acid.    What  is  the  color 
of  the  precipitate  formed?     What  does  it  indicate?     Write 
the  equation. 

When  hot  concentrated  nitric  acid  is  used  in  excess, 
mercuric  nitrate  is  formed  which  gives  no  precipitate 
when  treated  with  hydrochloric  acid.  Mercuric  chloride 
is  soluble. 

Iodine  as  a  Test  for  Oxidizing  and  Reducing  Agents. 

The  liberation  of  iodine  from  potassium  iodide  or 
hydriodic  acid  indicates  an  oxidizing  agent,  the  free 
iodine  is  recognized  by  the  brown  color  it  gives  to 
water;  and  the  wine  color  it  gives  to  kerosene,  carbon 
bisulphide,  etc.  The  test  can  be  made  more  delicate  by 
introducing  freshly  prepared  starch  paste  which  is  colored 


EXPERIMENTAL  CHEMISTRY  55 

blue  by  a  mere  trace  of  free  iodine.       (The  color  of  the 
iodide  of  starch  disappears  temporarily  while  heated.) 

Conversely,  the  removal  of  this  blue  color  generally 
indicates  a  reducing  agent. 

44..  (a)  Dissolve  a  small  crystal  of  potassium  iodide 
in  about  25CC  of  water,  or  take  5CC  of  the  prepared 
potassium  iodide  solution  and  dilute  it. 

Put  3  or  4CC  of  the  solution  into  each  of  three  test 
tubes,  and  add  to  each  about  2CC  of  kerosene  or  a  few 
drops  of  carbon  bisulphide.  Into  one  test  tube  add  a 
small  quantity  of  ferric  chloride  solution;  into  another,  a 
little  copper  sulphate  solution;  and  into  the  third,  dilute 
nitric  acid.  Observe  any  changes  in  appearance. 

(1)  Fe8Cl6+2KI=I2H-2KCl-f2FeCl2. 

(2)  2CuSO4-t-4KI=I2-|-2K2SO4-f-Cu2I2. 

(3)  4HNO3-f  3KI=IS-+  3KNO3+NO+2H2O. 

(b)  Prepare     some     starch    paste    and    add    some 
potassium   iodide    solution    to   it;     stir   well   and   keep 
covered.     Take   small   quantities   in  test  tubes  and  add 
mere  traces  of  the  following: 

(1)  Ferric  chloride,  (2)  copper  sulphate,  (3) 
mercuric  chloride,  (4)  chlorine  water,  (add  this  reagent 
drop  by  drop  and  finally  in  considerable  quantity). 
What  changes  do  you  notice? 

Heat  some  of  the  solutions  and  then  allow  them  to  cool. 
What  is  the  effect? 

HgCl2+2KI=2KCl-fHgI2. 

Cl-f  KI=KC1-|-I  (with  comparatively  little  chlorine). 

(c)  Make    some    of    the   starch    paste,     containing 
potassium    iodide,     blue    by  adding   a   drop   or   two  of 
bromine  or  chlorine  water. 

To  small  quantities  of  this  in  three  test  tubes,  add 
solutions  of  the  following: 


56  EXPERIMENTAL  CHEMISTRY 

(1)  Hydrogen  sulphide,  (2)  stannous  chloride,  (3) 
sodium  hydrate.  Is  there  any  change  in  color  produced? 

(1)  H2S+2I=2HI+S. 

(2)  2SnCl24-4I=SnCl4-fSnI4. 

(3)  6NaOH-f6I=r3H,O-j-5NaI+NaIO3. 

IRON. 

45.     (a)     What  is  the  color  of  a  freshly  broken  piece 
of  iron?     What  is  ''iron  rust"? 

Heat  a  little  ferric  chloride  (or  any  iron  compound) 
on  charcoal.  What  is  the  color  of  the  residue?  Allow  it 
to  cool  and  test  with  a  magnet.  Has  it  magnetic 
properties?  Try  another  compound. 

Examine  several  of  the  ferric  and  the  ferrous  salts  and 
solutions.  Can  you  make  any  distinction  as  to  color? 

IRON     COMPOUNDS     (OXIDATION     AND     REDUCTION). 

46.  (a)  Place  about  one-half  gram  of  fine  iron 
wire  or  filings  in  a  small  flask  and  add  about  50CC  of 
dilute  sulphuric  acid,  and  then  a  little  sodium  carbonate. 
(Carbon  dioxide  forms  and  expels  the  air. )  Insert  a 
delivery  tube  and  warm  gently  till  action  ceases. 

Carbon,  silicon,  etc.,  remain  undissolved.  What  is  in 
solution? 

Write  the  equation  representing  the  action  of 
sulphuric  acid  on  iron. 

Allow  the  undissolved  portion  to  settle,  and  then  pour 
off  the  clear  solution — one-half  into  a  beaker,  the  other 
half  into  a  bottle.  Dilute  the  solution  in  the  bottle  by 
adding  an  equal  volume  of  water;  add  a  pinch  of  sodium 
carbonate  to  displace  the  air,  and  when  action  ceases, 
cork  the  bottle. 

Heat  the  ferrous  sulphate  in  the  beaker  to  boiling  and 
add  4  or  5CC  of  concentrated  nitric  acid  and  evaporate  to 


EXPERIMENTAL  CHEMISTRY  57 

one-half.  If  necessary,  add  more  nitric  acid  and  boil 
again  until  you  notice  a  distinct  change  in  color.  Ferric 
sulphate  is  formed.  Observe  the  characteristic  colors  of 
ferrous  and  ferric  solutions. 

(b)  Take  about   a   cubic   centimeter   of  the  ferrous 
sulphate  solution  and   add  at  once  a  solution  of  sodium 
hydroxide;  ferrous  hydroxide  is  precipitated. 

Treat  a  similar  amount  of  ferric  sulphate  with  the 
sodium  hydroxide  solution;  ferric  hydroxide  is  precipitated. 
What  is  the  appearance  of  each  precipitate?  Write  the 
equation  expressing  the  reaction  in  each  case. 

Pour  a  little  of  the  ferrous  sulphate  solution  into  a 
test  tube  and  leave  it,  and  also  the  test  tube  containing  the 
ferrous  hydroxide,  open  to  the  air.  Shake  them  from 
time  to  time.  Do  you  notice  any  change?  What  forms 
in  each  case? 

(c)  1.  Treat  a  small  quantity  of  ferric  sulphate  with 
about  10CC  of  hydrogen  sulphide  solution;  warm  slightly. 
Fe2(SOJ3H-H2S==2FeSO4-4-H.,SO4-fS.  (white precipitate). 

2.  Place  a  piece  of  zinc  in  a  little  of  the  ferric 
sulphate  solution  and  leave  for  ten  minutes.  What  change 
do  you  notice?  Write  the  equation  expressing  the  reac- 
tion. 

Mention  several  oxidizing  agents,  and  several  reduc- 
ing agents. 

COPPER. 

47.  (a)  Examine  some  copper  wire  or  sheet  copper; 
also  examine  some  of  the  metallic  copper  in  the  stoppered 
bottle.  Is  there  any  difference  in  appearance  between 
that  in  the  bottle  and  that  exposed  to  the  moist  air  of  the 
room? 

Mention  any  uses  of  copper  with  which  you  are 
familiar. 


58  EXPERIMENTAL  CHEMISTRY 

Test  the  effect  of  the  common  acids,  both  the  concen- 
trated and  the  dilute,  upon  metallic  copper.  Does  heat 
modify  the  action?  • 

(b)  Examine  several  of  the  compounds  of  copper. 
Which    compound  have  you  already  examined,   and  for 
what  purpose? 

What  seems  to  be  the  general  color  of  the  solutions  of 
the  copper    compounds?       Take    a    copper    compound, 
moisten  a  little  with  hydrochloric  acid,  and  see  what  color 
it  gives  to  flames. 

Test  some  of  the  solutions  to  see  if  they  have  either 
an  acid  or  an  alkaline  reaction. 

(c)  How  is  copper  sulphate  made?     Obtain  some  of 
the  solution    and  pour  about  5CC  into   each   of  three  test 
tubes;  then  try  the  effect  of  each  of  the  following  solu- 
tions:   Potassium    hydroxide,    hydrogen    sulphide,     and 
potassium  ferrocyanide.     Give  the  color  of  each  precip- 
itate.    Write   the    equations    and    underline    the   parts 
representing  the  precipitates. 

Heat  the  test  tube  into  which  potassium  hydroxide 
was  added.  Copper  oxide  is  formed.  What  is  its  color? 
write  the  equation. 

EQUIVALENT   WEIGHT   OF   COPPER. 

48.  (a)  Brighten  some  narrow  strips  of  pure  zinc, 
and  weigh  out  exactly  one  gram.  Clean  thoroughly  a 
comparatively  large  evaporating  dish  and  place  the  zinc 
strips,  loosely  coiled,  in  the  bottom.  Weigh  on  a  rough 
balance  some  copper  sulphate  crystals,  about  ten  times 
the  weight  of  zinc  taken,  dissolve  in  about  100CC  of  hot 
water,  and  then  filter  the  hot  solution  upon  the  zinc  in  the 
basin.  Place  the  dish  on  your  ring-stand  on  a  wire  gauze 
and  heat  from  one  to  two  hours  (or,  if  more  convenient, 


EXPERIMENTAL  CHEMISTRY  59 

allow  it  to   remain    covered     till    the    next   laboratory 
period. )  until  the  deposit  ceases  to  increase. 

(b)  Allow  the  deposit  to  settle,  and  then  decant  off 
all  the  liquid  possible  through  a  filter  paper  into  a  large 
beaker.     Add  water  to  the  basin,  heat,  allow  the  copper 
to  settle,  and  decant  as  before.     Wash  the  copper  several 
times  in  this  manner  until  a  portion  of  the  wash  water  in 
a  test  tube  gives  no  turbidity  when  barium  chloride  is 
added.     Finally  transfer  the  copper  deposit  to  the  filter, 
wash  again  to  settle  it,   and  dry  in  an  oven  at  a  temper- 
ature not  above  100°. 

(c)  Carefully  transfer  the  metallic  copper  to  a  watch 
glass  and  weigh  accurately.     This  amount  of  copper  has 
been  replaced  by  one  gram  of  zinc.     Hence,  knowing  the 
equivalent   of  zinc   from  Experiment    15,    calculate  the 
equivalent  weight  of  copper. 

Copper  may  also  be  precipitated  from  its  salts  by  iron 
and  some  other  metals.  Hence  their  equivalent  weight 
may  be  determined  in  a  similar  manner. 

LEAD. 

49  (a)  Take  a  piece  of  metallic  lead  and  scrape  off 
the  outer  surface  with  a  knife.  What  is  its  color? 

What  is  the  appearance  of  lead  that  has  been  exposed 
to  the  air  for  some  time?  See  if  you  can  write  on  paper 
with  the  metal.  Will  the  common  acids  dissolve  lead? 
Try  them. 

(b)  Place  on  a  piece  of  charcoal  a  little  lead  sulphide 
(galena) .  Cover  it  with  sodium  carbonate  and  heat  in  the 
reducing  flame.  Note  the  color  of  the  sublimate  while 
hot  and  when  cold.  Is  it  volatile?  Remove  the  beads  of 
metal  and  test  properties.  Can  you  mark  on  paper  with 
them? 


60  EXPERIMENTAL  CHEMISTRY 

(c)  1.  Place  in  a  test  tube  apiece  of  bright  sheet 
zinc  and  pour  over  it  5  or  10CC  of  lead  acetate  solution. 
Set  the  tube  to  one  side  and  leave  undisturbed  for  some 
time.  Explain  the  action  that  has  taken  place.  Write 
the  equation. 

2.  Remove   the   zinc,   wash  thoroughly,   and  scrape 
the  deposit  off  into  a  test  tube.     Pour  enough  dilute  nitric 
acid  into  the  test  tube  to  cover  the  lead   deposit.     Warm 
slightly  and  as  soon  as  action  ceases,  dilute  to  about  10CC. 

3.  Divide  the  solution  into  four  parts.     To  one  part, 
add  hydrogen  sulphide  solution;    to   another,    sulphuric 
acid;  to  the  third,  potassium  chromate;  and  to  the  fourth, 
hydrochloric  acid.     What  is   the  color   of  the   sulphide? 
the  sulphate?    the  chromate?    and    the    chloride?     Write 
the  equations  expressing  the  reactions. 

4  Divide  the  chloride  into  two  parts,  and  test  the 
solubility  in  cold  water  and  in  hot  water.  Is  it  soluble? 

Divide  the  hot  solution  into  two  parts.  Allow  one 
part  to  cool,  and  add  potassium  bichromate  solution  to  the 
other.  What  are  the  results? 

SILVER. 

50.  (a)  Dissolve  half  of  a  silver  dime  in  a  little 
dilute  nitric  acid  in  a  beaker.  Warm  gently  till  action 
is  over,  then  evaporate  nearly  to  dryness  and  dilute  with 
100CC  of  water. 

The  solution  contains  silver  nitrate,  copper  nitrate, 
and  nitric  acid.  (Traces  of  gold  are  sometimes  found  in 
the  form  of  little  black  specks.  These  may  be  separated 
from  the  solution  by  filtering.)  Which  of  the  compounds 
gives  the  solution  its  color? 

All  United  States  silver  coins  are  alloyed  with  about 
10  per  cent,  of  copper. 


EXPERIMENTAL  CHEMISTRY  61 

Heat  the  solution  to  boiling,  add  hydrochloric  acid 
slowly,  and  stir  till  the  precipitate  gathers  in  a  lump. 
What  is  the  color  of  the  precipitate?  What  is  it?  What 
remains  in  solution?  Filter  out  the  precipitate  and  dry  in 
an  air  bath  heated  to  1UO°-110°.  When  the  precipitate  is 
dry,  mix  a  little  sodium  carbonate  with  it,  and  heat  on 
charcoal  in  the  reducing  flame  of  the  blowpipe.  White 
beads  of  metallic  silver  are  formed.  Remove  these 
carefully  from  the  charcoal  and  place  them  in  an 
evaporating  dish.  Dissolve  in  a  little  dilute  nitric  acid 
and  evaporate  to  dryness  in  a  water  bath.  What  is 
formed?  Dissolve  the  residue  in  water  and  filter  into  a 
bottle  of  dark  colored  glass,  or  a  bottle  covered  with  dark 
paper. 

(b)  Pour  about  one-half  cubic  centimeter  of  the 
clear  silver  nitrate  solution  into  each  of  three  test  tubes, 
and  add  5CC  of  water  to  each.  Now  add  sodium  chloride 
solution  to  one,  potassium  bromide  solution  to  another, 
and  potassium  iodide  solution  to  the  third.  Name  each 
precipitate  and  give  its  color? 

Expose  all  to  the  light  and  watch  closely  for  any 
changes. 

Silver  salts  are  used  extensively  in  photography  on 
account  of  the  change  produced  by  light. 

51.  (a)  Place  in  a  test  tube  a  strip  of  metallic  zinc 
and  pour  over  it  3  or  4CC  of  the  silver  nitrate  solution 
prepared  in  Experiment  50.  Let  it  stand  for  some  time 
without  disturbing.  Remove  the  strip  from  the  tube  and 
wash  thoroughly  with  water.  What  is  the  appearance  of 
the  deposit?  Scrape  it  off  and  dissolve  in  dilute  nitric 
acid. 

(b)  Divide  the  solution  into  two  parts  and  dilute 
each  with  about  5CC  of  water. 


62  EXPERIMENTAL  CHEMISTRY 

Add  a  few  drops  of  hydrochloric  acid  to  one  part. 
How  does  the  precipitate  compare  with  the  precipitate 
formed  in  (a)  Kxp.  50?  Divide  the  precipitate  into  three 
parts  and  test  its  solubility  in  hot  water,  nitric  acid  and 
in  ammonium  hydroxide.  Compare  with  lead  chloride, 
(c)  4,  Experiment  49. 

(c)  Take  the  other  part  of  the  silver  solution 
retained  from  (b),  and  add  a  little  hydrogen  sulphide 
solution.  What  is  the  color  of  the  precipitate?  What 
is  it? 

Divide  the  precipitate  into  three  parts.  Add  cold 
nitric  acid  to  one  part,  hot  nitric  acid  to  another,  and 
potassium  cyanide  to  the  third  part.  Note  results. 

MERCURY. 

52.  (a)  In  what  form  is  metallic  mercury?  Can 
you  mention  any  other  element  that  is  usually  in  the 
same  form?  What  is  the  appearance  of  mercury? 

(b)  Take  four  test  tubes:  put  a  piece  of  zinc  into  one, 
a  piece  of  iron  into  another,  a  piece  of  copper  into  a  third, 
and  a  piece  of  tin  into  the  fourth.     Cover  each  metal  with 
a  solution  of  mercurous  nitrate.     After   a  few  minutes, 
remove  the  metals  and  examine.      Rub  each  with  a  piece 
of  soft  cloth.     Are  all  permanently  affected? 

Drop  a  globule  of  metallic  mercury  upon  a  piece  of 
sheet  zinc  and  rub  it  with  a  cloth.  Do  you  obtain  the 
same  result  as  with  the  piece  of  zinc  previously  used? 

What  are  alloys  of  mercury  with  other  metals  called? 

(c)  Heat  a  little  mercuric  oxide   in  a  closed  tube. 
What  change  in  appearance  do  you  notice?     Explain  the 
change. 

For  what  purpose  has  mercuric  oxide  been  used 
before? 


EXPERIMENTAL  CHEMISTRY  63 

(d)  Mix  some  mercurous  chloride  (calomel)  with  a 
little  sodium  carbonate  and  heat  in  a  closed  tube      Is  the 
compound  reduced  to  the  metal? 

(e)  Put  a  globule  of  mercury  in  a  test  tube  and  dis- 
solve in  nitric  acid.     Dilute  and  then  add  a  few  drops  of 
hydrochloric  acid  to  the  solution.     What  is  the  color  of 
the  precipitate?     What  is  it? 

Divide  the  precipitate  into  two  parts:  add  a  little 
ammonium  hydroxide  to  one  part.  What  is  the  effect? 
Add  water  to  the  other  part  and  boil  it.  Compare  with 
the  solubility  of  lead  chloride  and  silver  chloride  in 
water,  (c)  4.  Exp.  49,  and  (b)  Exp.  51. 

How  could  you  separate  lead  nitrate,  silver  nitrate, 
and  mercurous  nitrate  from  one  another? 

Hydrochloric  acid  gives  no  precipitate  when  added  to 
mercuric  solutions. 

ACTION    OF    ACIDS    ON    THE    METALS. 

53.  (a)  In  every  case  brighten  metals  used  by  filing 
or  with  sand  paper. 

Put  into  a  test  tube  2CC  of  dilute  sulphuric  acid  and 
insert  a  small  piece  of  zinc.  Note  the  action.  Warm 
(not  boil)  the  acid — is  the  action  modified?  Add  more 
zinc  and  continue  heating;  can  action  be  carried  on 
indefinitely? 

(b)  Take  two  test  tubes  each  containing  about  5CC  of 
dilute  sulphuric  acid.     Put   a  piece   of  smooth  zinc  into 
each,  warm  slightly,  and  note  the  character  of  the  action. 

Drop  on  the  zinc  in  one  tube  a  piece  of  platinum  or 
copper  wire,  or  a  silver  coin;  in  the  other  tube  put  a 
small  crystal  (or  two  or  three  drops  of  a  solution)  of 
copper  sulphate.  Is  action  more,  or  less,  energetic? 

(c)  Cut  a  long,    narrow  strip  of  zinc,    about  10cm 


64  EXPERIMENTAL  CHEMISTRY 

by  3mm,  and  place  it  in  a  test  tube.       Add  enough  dilute 
sulphuric  acid  to  half  cover  the  zinc;  warm  gently. 

At  what  part  of  the  liquid  is  the  action  most 
energetic? 

(d)  Take   two   pieces    of    zinc  of    equal    size    and 
equal   thickness    (about  3cm  by    3mm),    and   fold  one  up 
closely  several  times. 

Place  both  in  dilute  sulphuric,  or  hydrochloric,  acid 
and  observe  which  dissolves  first.  Expain. 

(e)  Take  two  small  pinches  of  about  equal  size  of 
iron  filings;  place  in  test  tubes  and  add  to  each  about  5CC 
of  dilute  sulphuric,  or  hydrochloric,  acid.     Shake  or  stir 
continuously  the  contents  of  one  tube,  letting  the  other 
stand  in  the  rack.     Which  dissolves   first?     Suggest  the 
cause. 

(f)  Review  your  experiments  and  make  a  tabulated 
outline  of  the  action  of  concentrated,   moderately  strong 
(one  volume  of  concentrated  acid  to  one  of  water),   and 
dilute  sulphuric  acid;  nitric  acid;  and  hydrochloric  acid 
upon  the  following  metals:     zinc,  iron,  copper,  lead,  and 
mercury. 

Perform  tests  that  have  not  been  previously  made,  and 
repeat  tests  whenever  you  are  in  doubt  as  to  the  action. 

FORMATION    OF    THE    COMPOUNDS    OF    THE    METALS. 

A  number  of  the  compounds  of  the  metals  have  already 
been  considered;  a  few  of  these,  by  way  of  review,  and 
some  others  will  now  be  studied  according  to  their  classi- 
fication. These  will  be  sufficient  to  present  the  general 
methods  of  preparation. 

CHLORIDES. 

54.  (a)  What  compound  is  formed  when  zinc  is 
treated  with  hydrochloric  acid?  Review  (a)  Experiment  6. 


EXPERIMENTAL  CHEMISTRY  65 

(b)  Review    (b)  5,  Experiment  23,  and  state  what 
was  formed  when  you  did  the  experiment. 

(c)  Add    hydrochloric    acid    to  a    little  quicklime. 
What  takes  place?     Write  the  equation. 

(d)  What  takes  place  when  caustic  soda  is  treated 
with  hydrochloric  acid?     Review  (c)  Experiment  33. 

(e)  What  is  the  effect  of  adding  hydrochloric  acid 
to  calcium  carbonate?     See  (a)  Experiment  26. 

As  illustrated  above,  the  chlorides  are  made  by  treating 
the  metals  with  chlorine  or  hydrochloric  acid;  and  by 
treating  an  oxide,  hydroxide,  or  carbonate  (a  salt  of  a 
volatile  acid)  with  hydrochloric  acid. 

(f )  Are  the  chlorides  of  lead,   silver,   and  mercury 
soluble,  difficultly  soluble,  or  insoluble  in  water?    Review 
Exps.  49,  51,  52.     Test  the  solubility,  in  water,  of  several 
of  the  other  chlorides  of  the  metals.       Are  they  soluble 
or  insoluble? 

If  a  precipitate  is  formed  when  hydrochloric  acid  is 
added  to  a  solution,  what  metal  or  metals,  would  you  sup- 
pose to  be  present? 

OXIDKS. 

55.  (a)  Review  Experiments  4  and  8,  and  state 
how  the  metals,  iron  and  magnesium,  were  changed. 

(b)  What    takes    place    when    copper    hydrate    is 
heated?     Represent  the  change  by  an  equation.     Review 
(c)  Experiment  47. 

(c)  Put  some  lead  nitrate  in  an  ignition   tube  and 
heat.     Oxygen    and    nitrogen    peroxide    are   given   off 
leaving  lead  oxide  behind.      What  is  the  appearance  of 
the  residue? 

(d)  When  certain  carbonates   are   heated   strongly, 


66  EXPERIMENTAL  CHEMISTRY 

carbon  dioxide  is  given  off.     What  is  left?     How  is  lime 
made? 

From  the  above,  state  how  the  oxides  are  made. 

HYDROXIDES. 

56.  (a)   How  is  calcium  hydroxide  formed?    Review 
(a)  Experiment  40. 

(b)  Put  5CC  of  magnesium  sulphate  solution  in  a  test 
tube   and   add   sodium  hydroxide.     The    precipitate    is 
magnesium  hydroxide.     What  is  its  appearance?     Write 
the  equation  representing  the  reaction.     Is  the  precipitate 
soluble  in  hydrochloric  acid? 

What  chlorides  are  insoluble  or  difficultly  soluble  in 
water? 

(c)  Add    caustic    soda    solution    to    a    little  ferric 
chloride  solution  in  a  test  tube.     The  precipitate  is  ferric 
hydroxide.       What   is    its    color?      Compare   with   (b) 
Experiment  46.      Would  you  expect  it  to  be  soluble  in 
hydrochloric  acid?     Why? 

Observe  that  in  (b)  and  (c)  a  soluble  hydroxide  has 
been  added  to  solutions  containing  metals  whose  hydrox- 
ides are  insoluble;  hence,  the  insoluble  hydroxides  are 
precipitated. 

Name  the  soluble  hydroxides.  How  is  potassium 
hydroxide  made?  Do  all  the  hydroxides  turn  litmus 
blue? 

SULPHIDES. 

57.  (a)     How   is  ferrous  sulphide  made?      Review 
(d)    Experiment   2.       What   use    have   you   previously 
made  of  ferrous  sulphide? 

(b)  Heat  some  sulphur  to  near  boiling  and  introduce 
into  it  a  piece  of  bright  copper — copper  foil  or  sheet 


EXPERIMENTAL  CHEMISTRY 


ta 
t/N/ 


copper.       What    change    takes    place?       What    is    t 
product  called? 

(c)  Put  a  drop  or  two  of  sodium  sulphide  solution,  or 
hydrogen  sulphide  solution  (any  soluble  sulphide)  on  a 
bright  silver  coin,  and  leave  for  a  few  minutes.      Rinse 
the  coin  and  examine.     How   has  it  changed  in  appear- 
ance?    The  formation  is  silver  sulphide. 

(d)  Review  (c)  Exp.  31,  and  (c)  Exp.  39. 
How  may  the  sulphides  be  made? 

What  reagent  is  used  to  precipitate  the  sulphides 
which  are  soluble  in  hydrochloric  acid? 

NITRATES. 

58.  (a)  What  is  left  in  solution  when  a  silver  coin 
is  dissolved  in  nitric  acid.-*  See  (a)  Experiment  50. 

(b)  What   is  the   effect  of  adding   nitric  acid  to   a 
metal?     Review    (d)     Exp.    21;     (c)  Exp.  49;    and    (e) 
Exp.  52. 

(c)  What  is  formed   when    nitric   acid    acts    upon 
copper?     Review  Experiment  20. 

Write  the  equation  expressing  the  reactions  which 
take  place  when  nitric  acid  is  neutralized  with  ammonium 
hydroxide,  calcium  hydroxide,  and  potassium  hydroxide. 

(d)  Add  nitric  acid  to  a  little  sodium  carbonate  in  a 
test  tube.     What  is  the  result? 

(e)  What  is  the  effect  of  adding  sulphuric  acid  to 
sodium  nitrate?     Review  Experiment  21. 

Sulphuric  acid  decomposes  all  nitrates  liberating 
nitric  acid.  What  gas  is  given  off  when  a  nitrate  is 
heated  strongly  in  a  closed  tube? 

(f)  Heat  some   copper   nitrate   crystals  in  a   closed 
tube.     Does  the  salt  contain  water  of  crystallization? 

(g)  Try  the  solubility,  in  water,  of  a  number  of  the 
nitrates. 


68  EXPERIMENTAL  CHEMISTRY 

SULPHATES. 

59.  (a)  What  is  the  action  of  sulphuric  acid  on  the 
metallic  hydroxides?  What  is  the  color  of  copper  sul- 
phate? Does  the  removal  of  the  water  of  crystallization 
affect  the  form  or  color  of  the  crystals?  See  Experi- 
ment 14. 

(b)  Review   the   following   experiments,    and   state 
what  sulphates  were  formed  and  how:  Experiments  6,  15, 
21,  22,  and  32. 

(c)  Obtain  dilute  solutions  of  lead  nitrate,  strontium 
nitrate,   and  barium  chloride;  and  a  strong  solution    of 
calcium  chloride.     The  sulphates  of  lead,  strontium,  and 
barium  are  insoluble  in  water;  the  sulphate  of  calcium 
difficultly  soluble.     Hence  a  precipitate  is  formed  when 
sulphuric  acid  is  added  to  solutions  of  these  metals. 

Add  sulphuric  acid  to  the  solutions,  and  note  the 
color  of  each  precipitate. 

(d)  The  same  insoluble  sulphates  may  be  formed  by 
adding  any  soluble  sulphate  to  the  solutions. 

Obtain  a  number  of  the  sulphates  from  the  shelf  and 
test  their  solubility  in  water.  Then  take  samples  of  the 
solutions  named  in  (c)  and  form  the  sulphates  by  adding 
soluble  sulphates.  What  is  the  characteristic  test  for 
soluble  sulphates? 

(e)  Heat   some   iron   sulphate   on   charcoal  in   the 
reducing  flame.      Note   the   odor  of  the  gas  given   off. 
What  is  it?     Sulphates  of  all  the  heavy  metals  give  off 
the  same  gas. 

CARBONATES. 

60.  (a)  Review  Experiment  26.  What  carbonates  were 
formed  and  how?  How  is  sodium  carbonate  made? 

(b)     Test  the  solubility,  in  water,   of  the  carbonates 


EXPERIMENTAL  CHEMISTRY  69 

of  potassium,  sodium,  and  ammonium.     What  is  the  effect 
of  boiling  the  solutions? 

(c)  Test  the  solubility,  in  water,  of  other  carbonates. 

(d)  Obtain  solutions  of  the   following   compounds: 
Lead   nitrate,    iron   sulphate,    copper    sulphate,    barium 
chloride,  and  calcium  chloride.     Add  to  each  a  little  of  a 
solution   of  a  soluble  carbonate.       Precipitates  (carbon- 
ates of  the  metals)  will  be  formed  in  the  solution   of  all 
the  salts  of  the  metals  whose  carbonates  are  insoluble  in 
water. 

How  do  the  results  compare  with  the  tests  made  in  (c)? 
Filter  off  the  precipitates  in  each  case,  wash,   and  test 
for  carbonates  with  acids.     What  gas  is  given  off? 

(e)  What  is  usually  the  effect  of  heating  a  carbonate 
strongly?     Review  Experiment  55. 

CR  YST  ALUZ  ATION . 

'  'Crystals  are  solids  bounded  by  plane  faces  inclined 
at  definite  angles."  While  there  are  a  great  number  of 
forms  of  crystals,  it  has  been  found  that  every  form  can  be 
referred  to  one  or  other  of  six  systems.  But  crystals  of 
the  same  form  may  differ  widely  in  appearance  and  habit; 
for  example,  the  faces  may  be  unequally  developed,  but 
he  angles  remain  constant.  A  given  chemical  compound 
usually  crystallizes,  under  the  same  conditions,  in  the 
same  form.  The  form,  "habit,"  and  optical  properties  of 
a  crystal  serve  as  a  guide  to  its  composition. 

Crystallization  can  only  take  place  when  the  particles 
or  molecules  are  free  to  arrange  themselves.  The  most 
slowly  formed  crystals  are,  as  a  rule,  the  largest  and  most 
perfect. 

61.  (a)  Carefully  clean  and  dry  some  glass  plates 
and  put  on  them,  by  means  of  a  glass  rod  or  pipette,  a 


70  EXPERIMENTAL  CHEMISTRY 

large  drop  of  each  of  the  solutions  named  and  in  the  order 
given.  Use  saturated  solutions.  Sodium  chloride, 
potassium  bromide,  sodium  nitrate,  potassium  nitrate, 
potassium  chlorate,  mercuric  chloride,  ammonium  chlor- 
ide, copper  sulphate,  ferrous  sulphate,  zinc  sulphate, 
potash  alum,  ammonium  alum,  chrome  alum,  sulphur  (in 
carbon  bisulphide).  Leave  two  or  three  hours  and  then 
examine  with  a  lens.  Note  the  appearance  and  resem- 
blance of  crystals  of  certain  salts. 

Crystals  of  salts  of  similar  molecular  structure  often 
occur  in  the  same  or  very  similar  forms.  Such  crystals 
are  said  to  be  isomorphous;  thus,  all  the  alums  crystallize 
in  octahedra;  so  also  sodium  chloride,  potassium  chloride, 
potassium  bromide,  and  potassium  iodide  all  crystallize  in 
cubes. 

The  same  substance  may,  under  different  conditions, 
crystallize  in  two  or  more  distinct  forms, — e.  g.  sulphur 
(see  Bxp.  29.)  and  zinc  sulphate.  Such  substances  are 
said  to  be  dimorphous. 

Water  of  crystallization  is  essential  to  the  form  of  some 
crystals,  and  in  many  cases  to  the  color  (see  Exp.  59), 
while  other  crystals  contain  none.  (See  Experiment  12.) 

Crystals  may  be  obtained  from  the  gaseous  state  in  the 
case  of  those  substances  which  do  not  liquefy  before 
solidifying. 

(b)  Put  a  small  piece  of  iodine  in  a  watch  glass  and 
place  over  it  a  glass  plate;  warm  the  lower  glass  very 
gently. 

Notice  the  iodine  crystals  formed  on  the  glass  plate. 

From  a  mixed  solution  certain  salts  will  crystallize  out 
together  as  a  double  salt,  which  is  not  a  mere  mixture, 
as  the  number  of  molecules  bear  a  definite  ratio;  thus  a 
solution  of  the  sulphates  of  aluminum  and  potassium  yield, 


EXPERIMENTAL  CHEMISTRY  71 

upon  evaporation,  crystals   of  alum   of    the  composition 
K2SO4.A12(SO4)8.24H2O. 

Note  — A  solution  should  be  prepared,  concentrated, 
and  poured  into  a  shallow  crystallizing  dish  so  that  the 
class  may  observe  the  growth  of  the  crystals  from  day  to 
day.  The  temperature  must  not  fluctuate  if  good  crys- 
tals are  to  be  had. 

Crystals  deposited  from  impure  solutions  contain  less 
impurity  than  the  solution,  i.  e.  a  less  proportion;  hence 
crystallizable  soluble  substances  can,  by  repeated  solution 
and  partial  recrystallization,  be  almost  absolutely  free  from 
all  impurities  —  excepting  isomorphous  substances,  and 
those  salts  with  which  they  form  double  salts. 

DETERMINATION    OF    ATOMIC    WEIGHTS 

The  atoms  of  most  elements  in  the  solid  state  have 
approximately  the  same  capacity  for  heat;  as  their  atomic 
weights  increase,  their  specific  heats  decrease,  so  that  the 
product  of  the  atomic  weight  times  the  specific  heat 
approximates  to  a  constant  value.  The  average  value 
is  6.4. 

Hence,  atomic  weight  x  specific  heat=6.4. 

"The  equivalent  of  an  element  always  bears  some 
numerical  relation  to  its  atomic  weight.  As  a  rule,  this 
relation  is  a  simple  one.  With  hydrogen  and  chlorine, 
equivalent  and  atomic  weight  are  equal;  the  atomic 
weight  of  oxygen  is  twice  its  equivalent;  while  that  of 
nitrogen  is  three  times  its  equivalent." 

Elements  whose  equivalent  and  atomic  weight  are 
equal  are  called  Monads;  those  whose  atomic  weight  is 
twice  the  equivalet  are  called  Dyads;  etc. 

"The  word  Quantivalence  or  Valency  is  applied  to 
denote  generally  the  state  of  an  element  as  regards  its 
function  as  a  monad,  dyad,  etc." 


72  EXPERIMENTAL  CHEMISTRY 

The  valency  of  an  element,  then,  is  expressed  by  the 
number  of  times  which  the  equivalent  is  contained  in  the 
atomic  weight. 

As  the  product  6.4  varies  somewhat  with  different 
metals,  the  method  cannot  be  used  to  determine  atomic 
weights  exactly,  but  it  decides  whether  the  equivalent,  or 
combining  weight,  is  equal  to  the  atomic  weight,  or  is 
some  fractional  proportion  of  it. 

62.  (a)  Weigh  accurately  a  piece  of  metallic  copper 
(copper  wire  loosely  coiled  if  obtainable),  and  suspend  it 
by  a  fine  wire  in  a  beaker  of  boiling  water. 

Counterpoise  a  calorimeter,  and  then  add  somewhat 
more  than  enough  water  to  cover  the  metal, — take  a 
round  number  of  grams  (200,  300  or  500)  to  simplify 
calculations,  and  weigh  accurately. 

In  weighing  liquids  it  is  best  to  add  a  little  more  than 
the  desired  amount  and  remove  the  excess  by  absorbing 
it  with  a  piece  of  blotting  paper. 

Note  the  exact  temperature  of  the  water  in  the  calori- 
meter. Remove  the  copper  from  the  boiling  water,  jerk 
off  as  much  water  as  possible,  and  lower  it  immediately 
into  the  calorimeter.  Stir  the  water  with  the  metal  for 
about  a  minute.  Note  the  temperature  from  time  to  time 
and  take  the  highest  reading. 

Calculate  from  the  data  obtained  the  specific  heat  of 
copper. 

(b)  Determine,  in  a  similar  manner,  the  specific  heat 
of  tin  and  of  lead. 

(c)  Having  found  the  specific  heats  of  the   metals, 
calulate  from   the  formula  given  their  respective  atomic 
weights. 

Tabulate  the  values  found.  Write  the  names  of  the 
metals  (copper,  tin,  and  lead,  in  the  order  given)  in  the 


EXPERIMENTAL  CHEMISTRY  73 

first  column;  the  corresponding  atomic  weight  in  the 
second;  corresponding  specific  heat  in  the  third;  and  the 
product  of  the  atomic  weight  by  the  specific  heat  in  the 
fourth  column.  Get  the  average  of  the  three  products. 

Are  the  atomic  weights  of  the  metals  in  the  order  of 
magnitude,  or  not?  Are  the  specific  heats  in  the  same,  or 
the  reverse,  order? 

How  does  the  atomic  weight  of  copper  as  determined 
compare  with  its  equivalent  weight  found  in  Exper- 
iment 48? 


APPENDIX. 


TABLE    OF    COMMON    ELEMENTS.    . 

NAME,  SYMBOL,  AND  ATOMIC  WEIGHTS  IN  EVEN  NUMBERS- 

Aluminum Al...  27  Lead Pb...205 

Antimony Sb...l20  Magnesium  Mg..  24 

Arsenic As...  74  Manganese Mn  ..  55 

Barium Ba...l36  Mercury Hg..l99 

Bismuth BL..207  Nickel Ni...  58 

Boron.. B  ...   11  Nitrogen  N  ...   14 

Bromine Br...  80  Oxygen  O  ...  16 

Calcium Ca...  40  Phosphorus  P  ...  31 

Carbon C 12  Platinum Pt...l94 

Chlorine Cl...  35  Potassium K...  39 

Chromium Cr...  52  Silicon  Si...  28 

Cobalt Co...  59  Silver ....Ag..l07 

Copper Cu  ..  63  Sodium Na..  23 

Fluorine  F 19  Strontium Sr...  87 

Gold Au  ..196  Sulphur S 32 

Hydrogen , H...     1  Tin Sn...ll8 

Iodine I 126  Zinc Zn  ..  65 

Iron Fe...  56 

COMPLETE    LIST    OF    CHEMICALS    REQUIRED 
FOR    THE    COURSE. 

ESTIMATE    FOR    A    CLASS    OF     12. 

Antimony  chloride  ^  Ib. 

Antimony,  powdered  ^  Ib. 

Arsenic  chloride i  oz. 

Alcohol 4^  gal.  if  used  for  lamps 

Alum,  potash... %  Ib. 

"       chrome  %  "&. 

11       ammonium Ib. 


76  EXPERIMENTAL  CHEMISTRY 

Ammonium  hydrate,  cone 3  Ib. 

nitrate 2  Ib. 

sulphate  #  Ib. 

sulphide #  Ib. 

chloride %  Ib. 

carbonate  i  Ib. 

Barium  chloride ^  Ib. 

nitrate #  Ib. 

Bromine i   oz. 

Boneblack   ^   Ib. 

Borax  %  Ib. 

Calcium  oxide 2  Ib. 

carbonate,  lumps 2  Ib. 

chloride %  Ib. 

sulphate  #  Ib. 

Carbon  bisulphide ^   Ib. 

Cobalt  chloride i   oz. 

"      nitrate i   oz. 

Copper  oxide i  oz. 

sulphate,  pure ^  Ib. 

nitrate %   Ib. 

foil X   Ib. 

sheet  X  Ib. 

"         wire yz   Ib. 

Chlorine  water  (made  in  Lab.) 

Cochineal i   oz. 

Charcoal  2  doz.  sticks 

Candles .' ^   dozen 

Cotton  print few  pieces 

Cardboard few  pieces 

Ether ^  Ib. 

Ferrous  sulphate ^  Ib. 

sulphide 2  Ib. 


EXPERIMENTAL  CHEMISTRY  77 

Ferric  chloride 3  oz 

Filter  paper,   5  in.  diam 4  packages 

Gypsum,  powdered 4  oz. 

Hydrochloric  acid,  cone 6  Ib. 

Hydrogen  sulphide  (made  in  Lab.) 

Iron,  sheet i  Ib. 

"       filings,  fine i  Ib. 

Iodine i  oz. 

Indigo  solution %  Ib. 

Kerosene i  Ib. 

Lead  nitrate %  ft>- 

<l      acetate,  pure  %  Ib. 

"      sulphide #  Ib. 

11      sheet %  Ib. 

Litmus i  oz . 

Litmus  paper,  red  and  blue i  box  each 

Labels  i  box  each  of  large  and  small 

Magnesium  ribbon ^  oz. 

sulphate #  Ib. 

Manganese  dioxide,  coarse 2  Ib. 

Mercury  i   Ib. 

Mercurous  chloride i  oz. 

nitrate %  Ib. 

Mercuric  chloride X  Ik- 
Mercuric  oxide  X  Ik- 

Nitric  acid,  cone 6  Ib. 

Oxalic  acid  crystals  i  Ib. 

Oil  of  turpentine %  Ib. 

Paraffine  i  Ib. 

Phosphorus i  oz . 

Potassium,  metallic X  oz- 

hydrate,  sticks i  Ib. 

chloride Ib. 


78  EXPERIMENTAL  CHEMISTRY 

Potassium,  nitrate i   Ib. 

carbonate  X  Ib. 

iodide  X  Ib. 

bromide i   oz. 

'£  cyanide ^  Ib. 

permanganate %  Ib. 

bichromate .'. . .  ^  Ib. 

chlorate 2  Ib. 

chromate ^  Ib. 

ferrocyanide %  Ib. 

Platinum  foil 2  pieces  i   in.  square 

wire i  ft. 

Silk,  unbleached 25  cts 

Sodium,   metallic i   oz. 

chloride,  pure i  Ib. 

sulphide  i  oz. 

sulphate  ^  Ib. 

hydrate,  sticks i  Ib. 

nitrate 2  Ib. 

carbonate %  Ib. 

Sulphur,  roll y2  Ib. 

flowers y2  Ib. 

Sulphuric  acid,  cone 9  Ib. 

Stannous  chloride i  oz. 

Starch  y2  Ib. 

Strontium  nitrate %  Ib. 

Sugar i  Ib. 

Sealing  Wax  2  sticks 

Tin  foil,  pure #  Ib. 

Yarn,  white  woolen 10  cts. 

Zinc,  granulated 2  Ib. 

"      sheet  i  Ib. 

"      sulphate 


EXPERIMENTAL  CHEMISTRY  79 

APPARATUS. 

ESTIMATE   FOR   A   CLASS   OF   TWELVE   WITH    AN    ALLOW- 
ANCE  FOR   SOME    BREAKAGE. 

12  Asbestos  sheets  i  in.  thick,  4x4  in. 

1  Air-bath  (drying  oven.) 

2  Bell  jars,  $  gal. 
1  Balance,  rough. 

1  Balance,  delicate,  with  metric  weights. 
12  Blowpipes,  plain  with  moisture  bulb. 

2  doz.  Beakers,  3  to  7  oz. 
2  Burettes  100CC  each. 

2  pieces  Blue  Glass,  4x4  in. 

1  Barometer. 

6  Calcium  Chloride  U-tubes,  plain,  6  in. 
10  doz.  corks,  best  quality,   Nos.   3  to  10. 

2  doz.  corks,   1  to  2  in.  diameter. 

2  Condensers,   18  in.  long. 
1  doz.  Clamps,  small. 

4  Calorimeters,  metal. 

3  Crystallizing  dishes,  8  in.  diam. 
10  Deflagrating  spoons,  -J  in.  bowl. 
12  Delivery  tubes  (made  by  class). 

4  Desiccators,  4  in.  diam. 

1  Electric  battery,   2     cells. 

1  Electrolysis  apparatus,  simple  form. 

2  doz.  Evaporating  dishes,  2  and  3  oz. 
1-i  doz.  Flasks,  flat  bottom,   12  oz. 

^  doz.  Flasks,  flat  bottom  8  oz. 

1  doz.  Funnels  3-|  in.  diam. 

2  doz.  Funnel  tubes,  small,   10  in.  long. 
4  doz.  Files,  triangular,  6  in.  long. 


80  EXPERIMENTAL  CHEMISTRY 

3  Files,  rat  tail,  6  in.  long. 

1  doz.  Forceps,  common  steel,  4  in.  long. 

2  Graduated  cylinders,   50CC  and  200CC. 

2  Gasoline  Lab.  lamps,  Dangler's.   (Not  required  if  gas 

is  used.) 
1-J  doz.  Glass  stirring  rods,  solid  glass. 

2  Ib.  Glass  tubing,  hard  and  soft,  i  in.  diam. 

1  Ib.  Glass  tubing,  soft,  ^  and  -^    in.  diam. 

4  doz.  Glass  plates,  3x3  in. 

3  nests  Hessian  crucibles,  4  in  nest,  small  5s. 
-£  doz.  Iron  dishes,  4  in.  diam. 

2  doz.  Ignition  tubes,  4  and  6  in.  length. 

\  doz.  Iron  water  (or  gas)  pipes  50cm  x  2cm  diam. 
6  Metric  rulers. 

2  Mortars  and  pestles,  1  iron  2  pt.,  1  porcelain  4^  in. 
diam. 

2  Magnets,    horse  shoe,  4  in  long. 

1  Magnifying  glass. 

%  doz.  Porcelain  crucibles,   1-J  in.  diam. 

3  Porous  earthen  cups,  2  in.  diam.,  4  in.  long. 

2  Pipettes,  bulb. 

Pneumatic  troughs     (movable  shelf  for  each  basin). 
1^  doz.  Pinch-cocks,   Mohr's. 

12  Rubber  corks,  two  preforations,  for  12  oz.   flasks. 
40  ft.  Rubber  tubing,  20  ft.  i  in.;  10  ft.  -J  in;  10  ft.  —  in. 

3  Retorts,  glass,  4  oz.  Bohemian  glass. 
1  Retort,  copper,   1  qt. 

12  Supports,  iron  stands  with  two  rings  each. 
12  Spirit  lamps,  glass  globe  shape;  or  12  Bunsen  burn- 
ers if  gas  is  used. 

3  Sand  baths,  4  in.  diam. 

1  Spatula,   5  in.  blade. 

1  set  cork  borers,  6  in  a  set. 


EXPERIMENTAL  CHEMISTRY  81 

1  horn  spoon. 

10  doz.  Test  tubes;  two  doz.  each  of  4,  5,  6,  7  and  8  in. 

2  Thermometers,  200  degrees  Centigrade. 
\  doz.  Triangles,  wire  pipe  stem  covered. 

1  doz.  Test  Tube  racks,  for  13  tubes,  with  drying  pins. 

\  doz.  Test  tube  brushes,  with  sponge  on  end. 

1  doz.  Watch  glasses,  2^  in    diam. 

1  doz.  Wolff's  bottles,  two  necks,   4  oz.  each. 

1  doz.  Wire  gauze  5  in.  square. 

INDIVIDUAL     APPARATUS 

Each  pupil  should  be  provided    with    the    following 
apparatus  selected  from  the  preceding  list: 
1  Iron  stand  support  with  two  rings  and  one  clamp. 
1  Test  tube  rack. 
6  Test  tubes. 
1  Blowpipe. 
1  Stirring  rod. 
1   piece  asbestos 
1  Piece  wire  gauze. 
1   Watch  crystal 

1  ft.  6  in.   Rubber  tubing. 

2  short  pieces  rubber  tubing. 

1  Florence  flask  with  rubber  cork. 
1   Funnel  tube. 
1  Pinch-cock. 
1   Pair  forceps. 

3  Glass  plates. 

4  Wide-mouthed  bottles  or  cylinders  (furnished  by  pupil) . 
1  Evaporating  dish. 

1  Beaker. 
1  Glass  plug. 

A  few  pieces  of  red  and  blue  litmus  paper. 
1  Alcohol  lamp  or  Bunsen  burner. 


82  EXPERIMENTAL  CHEMISTRY 

PREPARATION   OF   SOLUTIONS. 

(a)  The  common  acids  (sulphuric,  nitric  and  hydro- 
chloric), and  ammonium  hydrate  purchased  from  dealers 
are  concentrated.     For   ordinary    use,    unless  otherwise 
indicated,    they  should  be  diluted  by  mixing  with  four 
times  their  volume  of  pure  water.       Small   bottles   (say, 
4  oz. )  of  these  reagents  should  be  kept  on  the  shelf  over 
the  student's  table. 

Great  care  should  be  taken  in  working  with  the  con- 
centrated liquids,  as  they  attack  the  skin  and  often  cause 
painful  burns  or  ulcers.  For  this  reason  it  is  well  for  the 
teacher  to  prepare  large  bottles  of  the  dilute  solutions  for 
the  student  to  use  in  filling  his  reagent  bottles.  Small 
bottles  of  the  concentrated  acids  should  also  be  filled  for 
the  student's  use. 

(b)  The  following  solutions  are  called   for    in    the 
course.     They  should  be  prepared,    filtered   into  bottles, 
and  placed  on  the   shelves  for  use  when  required.     Use 
30  to '50  grams  in  about  500CC  water: 

Ammonium  chloride,  NH4C1. 

Alum,  potash,  KA1  (SOJ2. 

Alum,  ammonium,  (NH4)Al(SO4).r 

Alum,  chrome,  KCr(SO4)2. 

Arsenic  chloride,  AsCl3.      (1). 

Antimony  chloride,  SbCl3.      (2). 

Barium  nitrate,  Ba(No3)2. 

Barium  chloride,   BaCl2. 

Copper  sulphate,  CuSo4. 

Cobaltous  chloride,  CoCl . 

Calcium  chloride,  CaCl2. 

Calcium  hydrate,  (lime-water)  Ca(OH)2. 

Ferric  chloride,  FeCl3. 


EXPERIMENTAL  CHEMISTRY  83 

Ferrous  sulphate,  FeSo^.     (3). 
Lead  nitrate,  Pb(NO3)2. 
Lead  acetate,  Pb(C2H3O,)2. 
Mercuric  chloride,  HgCl2. 
Mercurous  nitrate,  HgNO3.     (4). 
Magnesium  sulphate,   MgSO4. 
Potassium  hydrate,   KOH. 
Potassium  bichromate,  K2Cr207. 
Potassium  permanganate,  KMnO4. 
Potassium  Ferrocyanide,  KtFe(CN)(i. 
Potassium  Cyanide,  KCN. 
Potassium  chromate,  K2CrO4. 
Potassium  bromide   KBr. 
Potassium  iodide,  KI. 
Potassium  nitrate,  KNO3. 
Potassium  chlorate,  KC1O3. 
Sodium  chloride,  NaCl. 
Sodium  nitrate,  NaNO3. 
Sodium  hydrate,  NaOH. 
Sodium  carbonate.  Na,CO3. 
Sodium  sulphide,  Na,S. 
Strontium  nitrate,  Sr(NO3)2, 
Stannous  chloride,  SnCl,.      (5). 
Zinc  sulphate,  ZnSO4. 

(1)  Treat  the  solid  with  a  small  amount  of  water; 
with  much  water  it  is  changed  into  the  oxide  and  hydro- 
chloric acid. 

(2)  Called  butter  of  antimony.      Acidify  the  water 
with  a  considerable  amount  of  hydrochloric  acid.     It  may 
also  be  made  by  treating  the  metal  antimony  with  hydro- 
chloric acid  containing  a  little  nitric  acid. 

(3)  Ferrous  sulphate  oxidizes  when  left  in  solution; 
it  should  be  prepared  as  needed. 


84  EXPERIMENTAL  CHEMISTRY 

(4)  Dissolve    mercurous    nitrate    crystals    in    water 
acidified  with  nitric  acid.     It  may  be  made  by  treating 
mercury  with  a  small  amount  of  dilute  nitric  acid. 

(5)  Acidify  water    with    considerable  .  hydrochloric 
acid.     Pieces  of  metallic  tin  should  be  kept  in  the  bottle 
to  prevent  oxidation  to  some  extent.       Fresh   solutions 
should  be  prepared  occasionally. 

(c)  Ammonium  sulphide,  (NH4)2S.  See  Experiment 
39  (c)  for  method  of  preparation. 

Hydrogen  sulphide,  H,S.  See  method  of  preparation, 
Experiment  31. 

Cochineal  solution.  Pulverize  4  or  5  grams  of  cochi- 
neal, add  water,  allow  to  stand  for  some  time;  then  stir 

well  and  filter. 

» 

Iodine  solution.     Dissolve  the  solid  in  alcohol. 

Indigo  solution.  Slowly  add  2  or  3  grams  of  powdered 
indigo  to  about  10CC  concentrated  sulphuric  acid  in  an 
evaporating  dish.  Cover  the  dish  and  allow  it  to  stand 
two  or  three  days;  and  then  add  500CC  water,  stir  well, 
and  filter. 

Litmus  solution.  Pulverize  litmus  cubes  and  add 
water;  allow  to  stand  for  some  time,  stir  well  and  filter. 


EXPERIMENTAL  CHEMISTRY  85 

ADDRESSES    OF    SUPPLY    HOUSES. 

Catalogues,  from  the  following  houses  have  been 
received  by  the  writer: — 

JOHN   TAYLOR  &  Co., 

Corner  First  and  Mission  Sts., 
San  Francisco,   Cal. 

Also  Agent  for  ZIEGLER  ELECTRIC  Co., 
Boston,   Mass. 

ALFRED  L.  ROBBINS  Co., 

149  and  151  East  Huron  St , 

Chicago,   111. 
BAUCH   &   LOME   OPTICAL   Co., 

515-543  North  St.  Paul  St., 

Rochester,   N.  Y. 

THE  CHICAGO   LABORATORY  SUPPLY   &  SCALE  Co., 
31-45  Randolph  St., 
Chicago,   111. 

HENRY   HEIL   CHEMICAL   COMPANY, 
208-212  South  Fourth  St., 

St.  Louis,   Mo. 

F.    A.    BECKETT,    Agent  for  HENRY  HEIL  Co., 
220  Sutter  St., 

San  Francisco,   Cal. 

Supplies  may  also  be  purchased  of 
SALE  &  SON'S, 

220  South  Spring  St., 

Los  Angeles,   Cal 

The  author  has  had  occasion  to  deal  with  John 
Taylor  &  Co.,  San  Francisco;  and  with  Alfred  L. 
Robbins  Co.,  Chicago.  He  has  found  both  houses  to 
be  thoroughly  reliable. 

OF  TMC 


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